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July 1994
- 8 participants
- 8 discussions
Hi everybody, i'd like to know if the 'changed' attribute
for the network object is mandatory. RIPE-50.txt does not say anything.
and the DB software configuration file says it's mandatory.
Thanks,
Laurent
--
Laurent Joncheray, E-Mail: lpj(a)merit.edu
Merit Network Inc, 1071 Beal Avenue, Phone: +1 (313) 936 2065
Ann Arbor, MI 48109, USA Fax: +1 (313) 747 3745
"This is the end, Beautiful friend. This is the end, My only friend, the end" JM
2
1
22 Jul '94
On Thu, 21 Jul 1994 13:58:28 +0200, Tony Bates wrote the following:
Here the latest draft with the comments from Blasco. I would like
to have this agreed at the latest at the next RIPE meeting.
Comments are of course still welcome. However, I am about to
depart for a month so they will have to wait to be folded in.
Now I'd like to get your opinions about the proper way of achieving
this!
I strongly support Tony's (and Daniel's) view that failing to agree on
this soon would block much needed progress. So my proposal is that as
many of you as possible read the circulated documents, comment on them
to the DB-WG list and indicate whether you can agree on the documents
or whether you strongly object against the proposals.
More so as there is probably once again a good chance that the DB-Group
has to compete with some other show-stopper in Lisbon and we again have
a meeting that does not represent the community...
Wilfried.
--------------------------------------------------------------------------
Wilfried Woeber : e-mail: Wilfried.Woeber(a)CC.UniVie.ac.at
Computer Center - ACOnet :
Vienna University : Tel: +43 1 4065822 355
Universitaetsstrasse 7 : Fax: +43 1 4065822 170
A-1010 Vienna, Austria, Europe : NIC: WW144
--------------------------------------------------------------------------
1
0
22 Jul '94
= * > ....
= * > - A route/AS name attribute. You currently use the first line of the 'des
= * c'
= * > attribute to generate a name (with prtraceroute for instance). Having
= * > a separate name attribute can make the query of the server (whois or what
= * ever)
= * > easier since it doesn't require any parsing.
= *
= * I strongly agree.
= *
=Umm... do not see the need for routes to have names - doesn't effect
=prtraceroute or any other tool for that matter. Whats to parse in
=description ? It is there in the aut-num object so a tool uses it..and
=works as far as I can tell ?
=
=However, if the groups want this fine by me. Just I didn't hear any
=other votes for this until now.
...Well no strong feelings about introducing a name atrtribute, but I
don't see the need for it. It's very easy to spoil the first line for
the description and it's comparably easy to spoil the value for a name
attribute...
I think the issue here is to make people aware that these strings
(however they are stored) are used by software and shold give useful
*and concise* information.
Would some others, having strong feelings, please speak up?!
= * >
= * > - Include the time (hour, min, second) in the "changed" attribute. This i
= * s
= * > in case of several changes in the same day. Proposed syntax
= * > (compatible with the older one):
= * >
= * > changed: <email> YYMMDD [hh:mm:ss] [+oo]
= * >
= * > If hh:mm:ss is missing we assume 00:00:00 +00 ???
= * > +oo if the offset from GMT. (i know, we have to deal with the times
= * > zones :-)
= *
= * I agree not because I think that frequent updates are necessary but because
= * including the time zone better identifies the exact time of the update.
= *
=
=Makes no odds to me either way. The software allows more than one
=update a day so this is a misnomer from Laurent.
=However, this is VERY much a general database issue and not at all in
=context with the ripe-81++ proposal I am afraid. DB chair what say you ?
There are two aspects to it:
- 1) do we need it? do we have to specify implementation?
- 2) if we need it - what do we want?
1) My personal opinion is (shaped by the experience of dealing
regularly with a *very reliable* RIPE-DB implementation) that we don't
need this gadget. Given the responsiveness of the overall system I
won't come to think of submitting another update before I've checked
the reply from the database! So I think it's an issue of trying to
solve the problem only when we have proof that it is there.
And - btw - I strongly advocate keeping the possibility to submit more
than one update per day!!! I consider this a feature, not a bug.
2) *IF* and when we decide to implement finer granularity, then I
think wiring in the weirdness of timezones (to DST or not to DST :-)
is definitely a *bad* idea! Do we really need time-information? If
this is the case then we should agree on UTC.
But I think what Laurent is perhaps advocating is something like an
update sequence number. So my proposal would be to add an *optional*
(positive, integer :-) sequence number with no other restrictions like
being contiguous etc. much like the DNS serial numbers.
Wilfried.
--------------------------------------------------------------------------
Wilfried Woeber : e-mail: Wilfried.Woeber(a)CC.UniVie.ac.at
Computer Center - ACOnet :
Vienna University : Tel: +43 1 4065822 355
Universitaetsstrasse 7 : Fax: +43 1 4065822 170
A-1010 Vienna, Austria, Europe : NIC: WW144
--------------------------------------------------------------------------
1
0
Find below the latest and hopefully last iteration of ripe-81++. We
have ratified all the outstanding issues with the possible exception
of the ordering of the interas-in/interas-out attribute which is not a
`show-stopper' at this point. We have used our preferred
syntax "for now" for clarity reasons. Anyway, here it is. We must reach
agreement on this at the RIPE meeting if this is to be implemented in
a timely manner and preferably before. Working group chairs please
take note and see if you can't get this agreed within your groups
before hand.
The major changes from the last draft is the inclusion of the
interas-in/interas-out work and pointers to the `inet-rtr'
object (already circulated).
versions online as usual from:
ftp://ftp.ripe.net/ripe/drafts/ripe-81++.ps
ftp://ftp.ripe.net/ripe/drafts/ripe-81++.txt
All comments welcome.
Enjoy !
Regards,
--Tony.
Representation of IP Routing Policies
in a Routing Registry
(ripe-81++)
DRAFT DRAFT DRAFT
Tony Bates
Elise Gerich
Laurent Joncheray
Jean-Michel Jouanigot
Daniel Karrenberg
Marten Terpstra
Jessica Yu
Document-ID: ripe-1nn
Obsoletes: ripe-81
July, 1994
ABSTRACT
This document is an update to the original `ripe-
81'[1] proposal for representing and storing routing
polices within the RIPE database. It incorporates
several extensions proposed by Merit Inc.[2] and gives
details of a generalised IP routing policy representa-
tion to be used by all Internet routing registries. It
acts as both tutorial and provides details of database
objects and attributes that use and make up a routing
registry.
ripe-1nn.txt July, 1994
- 2 -
Table of Contents
1 Introduction ................................................ ?
2 Organisation of this Document ............................... ?
3 General Representation of Policy Information ................ ?
4 The Routing Registry and the RIPE Database .................. ?
5 The Route Object ............................................ ?
6 The Autonomous System Object ................................ ?
7 The AS Macro Object ......................................... ?
8 The Community Object ........................................ ?
9 Representation of Routing Policies .......................... ?
10 Future Extensions .......................................... ?
11 References ................................................. ?
12 Authors Addresses .......................................... ?
Appendix A - Syntax for the "aut-num" object .................. ?
Appendix B - Syntax for the "community" object ................ ?
Appendix C - Syntax for the "as-macro" object ................. ?
Appendix D - Syntax for the "route" object .................... ?
Appendix E - List of reserved words ........................... ?
Appendix F - Motivations for RIPE-81++ ........................ ?
Appendix G - Transition strategy from RIPE-81 to RIPE-81++ .... ?
ripe-1nn.txt July, 1994
- 3 -
1. Introduction
This document is a much revised version of the RIPE routing registry
document known as ripe-81[1]. Since its inception in February, 1993
and the establishment of the RIPE routing registry, several addi-
tions and clarifications have come to light which can be better
presented in a single updated document rather than separate addenda.
Some of the text remains the same the as the original ripe-81 docu-
ment keeping its tutorial style mixed with details of the RIPE data-
base objects relating to routing policy representation. However
this document does not repeat the background and historical remarks
in ripe-81. For these please refer to the original document. It
should be noted that whilst this document specifically references
the RIPE database and the RIPE routing registry one can easily read
"Regional routing registry" in place of RIPE as this representation
is certainly general and flexible enough to be used outside of the
RIPE community incorporating many ideas and features from other
routing registries in this update.
As you can see this document has a new RIPE document identification
number but can also be referred to as ripe-81++. Appendix F summar-
ises the changes from ripe-81 plus the motivation for these changes.
We would like to acknowledge many people for help with this docu-
ment. Specifically, Peter Lothberg who was a co-author of the ori-
ginal ripe-81 document for his many ideas and Gilles Farrache. We
would also like to thank the RIPE routing working group for their
review and comment. Finally, we like to thank Merit Inc. for many
constructive comments and ideas and making the routing registry a
worldwide Internet service. We would also like to acknowledge the
funding provided by the PRIDE project run in conjunction with the
RARE Technical Program, RIPE and the RIPE NCC without which this
paper would not have been possible.
2. Organisation of this Paper
This paper acts as both a basic tutorial for understanding routing
policy and provides details of objects and attributes used within an
Internet routing registry to store routing policies. Section 3
describes general issues about IP routing policies and their
representation in routing registries. Experienced readers may wish
to skip this section. Section 4 provides an overview of the RIPE
database, its basic concepts, schema and objects which make up the
database itself. It highlights the way in which the RIPE database
splits routing information from allocation information. Sections 5,
6, 7 and 8 detail all the objects associated with routing policy
representation. Section 9 gives a fairly extensive "walk through"
of how these objects are used for expressing routing policy and the
general principles behind their use. Section 10 provides a list of
references used throughout this document. Appendix A, B, C and D
document the formal syntax for the database objects and attributes.
Appendix F details the main changes from ripe-81 and motivations for
these changes. Appendix G tackles the issues of transition from
ripe-1nn.txt July, 1994
- 4 -
ripe-81 to ripe-81++.
ripe-1nn.txt July, 1994
- 5 -
3. General Representation of Policy Information
Networks, Network Operators and Autonomous Systems
Throughout this document an effort is made to be consistent with
terms so as not to confuse the reader.
When we talk about "networks" we mean physical networks which have a
unique classless IP network number: Layer 3 entities. We do not mean
organisations.
We call the organisations operating networks "network operators".
For the sake of the examples we divide network operators into two
categories: "service providers" and "customers". A "service pro-
vider" is a network operator who operates a network to provide
Internet services to different organisations, its "customers". The
distinction between service providers and customers is not clear
cut. A national research networking organisation frequently acts as
a service provider to Universities and other academic organisations,
but in most cases it buys international connectivity from another
service provider. A University networking department is a customer
of the research networking organisation but in turn may regard
University departments as its customers.
An Autonomous System (AS) is a group of IP networks having a single
clearly defined routing policy which is run by one or more network
operators. Inside ASes IP packets are routed using one or more Inte-
rior Routing Protocols (IGPs). In most cases interior routing deci-
sions are based on metrics derived from technical parameters like
topology, link speeds and load(1).
ASes exchange routing information with other ASes using Exterior
Routing Protocols (EGPs). Exterior routing decisions are frequently
based on policy based rules rather than purely on technical parame-
ters. Tools are needed to configure complex policies and to commun-
icate those policies between ASes while still ensuring proper opera-
tion of the Internet as a whole. Some EGPs like BGP-3 [8] and BGP-4
[9] provide tools to filter routing information according to policy
rules and more. None of them provides a mechanism to publish or com-
municate the policies themselves. Yet this is critical for opera-
tional coordination and fault isolation among network operators and
thus for the operation of the global Internet as a whole. This
document describes a "Routing Registry" providing this functional-
ity.
_________________________
(1) The entity we refer to as an AS is frequently and
more generally called a routing domain with the AS just
being an implementation vehicle. We have decided to use
the term AS exclusively because it relates more direct-
ly with the database objects and routing tools. By us-
ing only one term we hope to reduce the number of con-
cepts and to avoid confusion. The academically inclined
reader may forgive us.
ripe-1nn.txt July, 1994
- 6 -
Routing Policies
The exchange of routing information between ASes is subject to rout-
ing policies. Consider the case of two ASes, X and Y exchanging
routing information:
NET1 ...... ASX <---> ASY ....... NET2
ASX knows how to reach a network called NET1. It does not matter
whether NET1 is belonging to ASX or some other AS which exchanges
routing information with ASX either directly or indirectly; we just
assume that ASX knows how to direct packets towards NET1. Likewise
ASY knows how to reach NET2.
In order for traffic from NET2 to NET1 to flow between ASX and ASY,
ASX has to announce NET1 to ASY using an external routing protocol.
This states that ASX is willing to accept traffic directed to NET1
from ASY. Policy thus comes into play first in the decision of ASX
to announce NET1 to ASY.
In addition ASY has to accept this routing information and use it.
It is ASY's privilege to either use or disregard the information
that ASX is willing to accept traffic for NET1. ASY might decide not
to use this information if it does not want to send traffic to NET1
at all or if it considers another route more appropriate to reach
NET1.
So in order for traffic in the direction of NET1 to flow between ASX
and ASY, ASX must announce it to ASY and ASY must accept it from
ASX:
resulting packet flow towards NET1
<<===================================
|
|
announce NET1 | accept NET1
--------------> + ------------->
|
AS X | AS Y
|
<------------- + <--------------
accept NET2 | announce NET2
|
|
resulting packet flow towards NET2
===================================>>
Ideally, and seldom practically, the announcement and acceptance
policies of ASX and ASY are identical.
ripe-1nn.txt July, 1994
- 7 -
In order for traffic towards NET2 to flow, announcement and accep-
tance of NET2 must be in place the other way round. For almost all
applications connectivity in just one direction is not useful at
all.
It is important to realise that with current destination based for-
warding technology routing policies must eventually be expressed in
these terms. It is relatively easy to formulate reasonable policies
in very general terms which CANNOT be expressed in terms of announc-
ing and accepting networks. With current technology such policies
are almost always impossible to implement.
Usually policies are not configured for each network separately but
for groups of networks. In practise these groups are almost always
defined by the networks forming one or more ASes.
Routing Policy limitations
The generic example of a reasonable but un-implementable routing is
a split of already joined packet streams based on something other
than destination address. Once traffic for the same destination
network passes the same router, or the same AS at our level of
abstraction, it will take exactly the same route to the destina-
tion(2).
In a concrete example AS Z might be connected to the outside world
by two links. AS Z wishes to reserve these links for different
kinds of traffic, let's call them black and white traffic. For this
purpose the management of AS Z keeps two lists of ASes, the black
and the white list. Together these lists comprise all ASes in the
world reachable from AS Z.
"W"
<--->
... AS Z .... NET 3
<--->
"B"
It is quite possible to implement the policy for traffic originating
in AS Z: AS Z will only accept announcements for networks in white
ASes on the white link and will only accept announcements for net-
works in black ASes on the black link. This causes traffic from
networks within AS Z towards white ASes to use the white link and
likewise traffic for black ASes to use the black link.
Note that this way of implementing things makes it necessary to
decide on the colour of each new AS which appears before traffic can
be sent to it from AS Z. A way around this would be to accept only
_________________________
(2) Disregarding special cases like "type of service"
routing, load sharing and routing instabilities.
ripe-1nn.txt July, 1994
- 8 -
white announcements via the white link and to accept all but white
announcements on the black link. That way traffic from new ASes
would automatically be sent down the black link and AS Z management
would only need to keep the list of white ASes rather than two
lists.
Now for the unimplementable part of the policy. This concerns
traffic towards AS Z. Consider the following topology:
B AS ---) "W"
W AS ---) --->
B AS ---)>> AS A ---> ... AS Z .... NET 3
B AS ---) --->
W AS ---) "B"
As seen from AS Z there are both black and white ASes "behind" AS A.
Since ASes can make routing decisions based on destination only, AS
A and all ASes between AS A and the two links connecting AS Z can
only make the same decision for traffic directed at a network in AS
Z, say NET 3. This means that traffic from both black and white
ASes towards NET 3 will follow the same route once it passes through
AS A. This will either be the black or the white route depending on
the routing policies of AS A and all ASes between it and AS Z.
The important thing to note is that unless routing and forwarding
decisions can be made based on both source and destination
addresses, policies like the "black and white" example cannot be
implemented in general because "once joined means joined forever".
Access Policies
Access policies contrary to routing policies are not necessarily
defined in terms of ASes. The very simplest type of access policy is
to block packets from a specific network S from being forwarded to
another network D. A common example is when some inappropriate use
of resources on network D has been made from network S and the prob-
lem has not been resolved yet. Other examples of access policies
might be resources only accessible to networks belonging to a par-
ticular disciplinary group or community of interest. While most of
these policies are better implemented at the host or application
level, network level access policies do exist and are a source of
connectivity problems which are sometimes hard to diagnose. There-
fore they should also be documented in the routing registry accord-
ing to similar requirements as outlined above.
Routing v Allocation information
The RIPE database contains both routing registry and address space
allocation registry information. In the past the database schema
combined this information. Because RIPE was tasked with running both
an allocation and routing registry it seemed natural to initially
ripe-1nn.txt July, 1994
- 9 -
combine these functions. However, experience has shown that a clear
separation of routing information from allocation is desirable.
Often the maintainer of the routing information is not the same as
the maintainer of the allocation information. Also, in other parts
of the world there are different registries for each kind of infor-
mation.
Whilst the actual routing policy objects will be introduced in the
next section it is worthy of note that a transition from the current
objects will be required. This is described with in Appendix G.
This split in information represents a significant change in the
representational model of the RIPE database. Appendix F expands on
the reasons for this a little more.
Tools
The network operators will need a series of tools for policy rout-
ing. Some tools are already available to perform some of the tasks.
Most notably, the PRIDE tools [3] from the PRIDE project started in
September 1993 as well as others produced by Merit Inc [4] and CERN
[5].
These tools will enable them to use the routing policy stored in the
RIPE routing registry to perform such tasks as check actual routing
against policies defined, ensure consistency of policies set by dif-
ferent operators, and simulate the effects of policy changes.
Work continues on producing more useful tools to service the Inter-
net community.
ripe-1nn.txt July, 1994
- 10 -
4. The Routing Registry and the RIPE Database
One of the activities of RIPE is to maintain a database of Euro-
pean IP networks, DNS domains and their contact persons along with
various other kinds of network management information. The database
content is public and can be queried using the whois protocol as
well as retrieved as a whole. This supports NICs/NOCs all over
Europe and beyond to perform their respective tasks.
The RIPE database combines both allocation registry and routing
registry functions. The RIPE allocation registry contains data
about address space allocated to specific enterprises and/or
delegated to local registries as well as data about the domain name
space. The allocation registry is described in separate documents
[6,7] and outside the scope of this document.
Database Objects
Each object in the database describes a single entity in the real
world. This basic principle means that information about that
entity should only be represented in the corresponding data-
base object and not be repeated in other objects. The whois ser-
vice can automatically display referenced objects where appropriate.
The types of objects stored in the RIPE database are summarised in
the table below:
R Object Describes References
____________________________________________________________________
B person contact persons
A inetnum IP address space person
A domain DNS domain person
R aut-num autonomous system person
(aut-num,community)
R as-macro a group of autonomous systems person, aut-num
R community community person
R route a route being announced aut-num, community
R clns CLNS address space and routing person
The first column indicates whether the object is part of the alloca-
tion registry (A), the routing registry (R) or both (B). The last
column indicates the types of objects referenced by the particular
type of object. It can be seen that almost all objects reference
contact persons.
Objects are described by attributes value pairs, one per line.
Objects are separated by empty lines. An attribute that consists
ripe-1nn.txt July, 1994
- 11 -
of multiple lines should have the attribute name repeated on
consecutive lines. The information stored about network 192.87.45.0
consists of three objects, one network object and two person
objects and looks like this:
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
person: Daniel Karrenberg
address: RIPE Network Coordination Centre (NCC)
address: Kruislaan 409
address: NL-1098 SJ Amsterdam
address: Netherlands
phone: +31 20 592 5065
fax-no: +31 20 592 5090
e-mail: dfk(a)ripe.net
nic-hdl: DK58
changed: ripe-dbm(a)ripe.net 920826
source: RIPE
person: Marten Terpstra
address: RIPE Network Coordination Centre (NCC)
address: PRIDE Project
address: Kruislaan 409
address: NL-1098 SJ Amsterdam
address: Netherlands
phone: +31 20 592 5064
fax-no: +31 20 592 5090
e-mail: Marten.Terpstra(a)ripe.net
nic-hdl: MT2
notify: marten(a)ripe.net
changed: marten(a)ripe.net 931230
source: RIPE
Objects are stored and retrieved in this tag/value format. The RIPE
NCC does not provide differently formatted reports because any
desired format can easily be produced from this generic one.
ripe-1nn.txt July, 1994
- 12 -
Routing Registry Objects
The main objects comprising the routing registry are "aut-num" and
"route", describing an autonomous system and a route respectively.
It should be noted that routes not described in the routing registry
should never be routed in the Internet itself.
The autonomous system (aut-num) object provides contact information
for the AS and describes the routing policy of that AS. The routing
policy is described by enumerating all neighbouring ASes with which
routing information is exchanged. For each neighbour the routing
policy is described in terms of exactly what is being sent
(announced) and allowed in (accepted). It is important to note that
this is exactly the part of the global policy over which an AS has
direct control. Thus each aut-num object describes what can indeed
be implemented and enforced locally by the AS concerned. Combined
together all the aut-num objects provide the global routing graph
and permit to deduce the exact routing policy between any two ASes.
While the aut-num objects describe how routing information is pro-
pagated, the route object describes a single route injected into the
external routing mesh. The route object references the AS injecting
(originating) the route and thereby indirectly provides contact
information for the originating AS. This reference also provides the
primary way of grouping routes into larger collections. This is
necessary because describing routing policy on the level of single
routes would be awkward to impractical given the number of routes in
the Internet which is about 20,000 at the time of this writing.
Thus routing policy is most often defined for groups of routes by
originating AS. This method of grouping is well supported by
current exterior routing protocols. The route object also refer-
ences community objects described below to provide another method of
grouping routes. Modification of aut-num object itself and the
referencing by route objects is strictly protected to provide net-
work operators control over the routing policy description and the
routes originated by their ASes.
Sometimes even keeping track of groups of routes at the AS level is
cumbersome. Consider the case of policies described at the transit
provider level which apply transitively to all customers of the
transit provider. Therefore another level of grouping is provided by
the as-macro object which provides groups of ASes which can be
referenced in routing policies just like single ASes. Membership of
as-macro groups is also strictly controlled.
Sometimes there is a need to group routes on different criteria than
ASes for purposes like statistics or local access policies. This is
provided by the community object. A community object is much like
an AS but without a routing policy. It just describes a group of
routes. This is not supported at all by exterior routing protocols
and depending on aggregation of routes may not be generally usable
to define routing policies. It is suitable for local policies and
non-routing related purposes.
ripe-1nn.txt July, 1994
- 13 -
These routing related objects will be described in detail in the
sections below.
ripe-1nn.txt July, 1994
- 14 -
5. The Route Object
As stated in the previous chapter routing and address space alloca-
tion information are now clearly separated. This is performed with
the introduction of the route object. The route object will contain
all the information regarding a routing announcement.
All routing related attributes are removed from the inetnum object.
Some old attributes are obsoleted: connect, routpr-l, bdryg-l, nsf-
in, nsf-out, gateway). The currently useful routing attributes are
moved to the route object: aut-sys becomes origin, ias-int will be
encoded as part of the "to be proposed" `border-router' object and
comm-list simply moves. See [6] for detail of the "inetnum" object
definition.
The information in the old inetnum object
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
connect: RIPE NSF WCW
aut-sys: AS3333
comm-list: SURFNET
ias-int: 192.87.45.80 AS1104
ias-int: 192.87.45.6 AS2122
ias-int: 192.87.45.254 AS2600
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
will be distributed over two objects:
ripe-1nn.txt July, 1994
- 15 -
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
route: 192.87.45.0/24
descr: RIPE Network Coordination Centre
origin: AS3333
comm-list: SURFNET
changed: dfk(a)ripe.net 940427
source: RIPE
The route object is used to represent a single route originated into
the Internet routing mesh. The actual syntax is given in Appendix
D. However, there are several important aspects of the attributes
worthy of note.
The value of the route attribute will be a classless address. It
represents the exact route being injected into the routing mesh.
The representation of classless addresses is described in [10].
The value of the origin attribute will be an AS reference of the
form AS1234 referring to an aut-num object. It represents the AS
injecting this route into the routing mesh. The "aut-num" object
(see below) thus referenced provides all the contact information for
this route.
Special cases: There can only be a single originating AS in each
route object. However in todays Internet sometimes a route is
injected by more than one AS. This situation is potentially
dangerous as it can create conflicting routing policies for that
route and requires coordination between the originating ASes. In
the routing registry this is represented by multiple route objects.
This is a departure from the one route (net), one AS principle of
the ripe-81 routing registry. The consequences for the different
tools based in the routing registry will need to be evaluated and
possibly additional consistency checking of the database is needed.
ripe-1nn.txt July, 1994
- 16 -
The examples below will illustrate the usage of the route object
further. Suppose three chunks of address space of 2 different
enterprises represented by the following inetnum objects:
Examples
inetnum: 193.0.1.0
netname: ENT-1
descr: Enterprise 1
...
inetnum: 193.0.8.0
netname: ENT-2
descr: Enterprise 2
...
inetnum: 193.0.9.0
netname: ENT-2-SPEC
descr: Enterprise 2
...
Supposing that the Enterprises have their own AS numbers straight
application of routing without aggregation would yield:
route: 193.0.1.0/24
descr: Enterprise 1
origin: AS1
...
route: 193.0.8.0/24
descr: Enterprise 2
origin: AS2
...
route: 193.0.9.0/24
descr: Enterprise 2
origin: AS2
...
NB: This representation can be achieved by straight translation from
the ripe-81 representation. See Appendix G for more details.
Homogeneous Aggregation
The two chunks of address space of Enterprise 2 can be represented
by one aggregate route turning two route objects into one and poten-
tially saving routing table space for one route.
ripe-1nn.txt July, 1994
- 17 -
route: 193.0.8.0/23
descr: Enterprise 2
origin: AS2
...
Note that AS2 can also decide to originate all routes mentioned so
far, two 24-bit prefixes and one 23-bit prefix. This case would be
represented by storing all three route objects in the database. In
this particular example the additional routes will not add any func-
tionality however and only increase the amount of routes announced
unnecessarily.
Heterogeneous Aggregation
Consider the following case however:
route: 193.0.8.0/24
descr: Enterprise 2
origin: AS2
...
route: 193.0.9.0/24
descr: Enterprise 2 / Special
origin: AS2
comm-list: SPECIAL
...
Now the prefix 193.0.9.0/24 belongs to community SPECIAL (this com-
munity may well not be relevant to routing) and the other prefix
originated by AS2 does not. If AS2 aggregates these prefixes into
the 193.0.8.0/23 prefix, routing policies based on the community
value SPECIAL cannot be implemented in general, because there is no
way to distinguish between the special and the not-so-special parts
of AS2. If another AS has the policy to accept only routes to
members of community SPECIAL it cannot implement it, because accept-
ing the route to 193.0.8.0/23 would also route to 193.0.8.0/24 and
not accepting this route would lose connectivity to the special part
193.0.9.0/24. We call aggregate routes consisting of components
belonging to different communities or even different ASes "hetero-
geneous aggregates".
The problems introduced with heterogeneous aggregates are that once
the homogeneous routes are withdrawn one cannot tell if a more
specific part of the heterogeneous has a different policy. However,
if can be counter argued that knowing this policy is of little use
if you cannot implement a routing policy based on the less specific
(and only route present) heterogeneous aggregate. In fact, this
displays a facet of CIDR itself in that one may actually compromise
slight variations on policy over announcing a larger (albeit
ripe-1nn.txt July, 1994
- 18 -
heterogeneous in terms of policy) aggregate to save address space.
However, it is still useful to be able to document these variations
in policy especially when this homogeneous more specific route is
just being withdrawn. For this one can use the "withdrawn" attri-
bute. The withdrawn attribute can serve to both indicate that a less
specific aggregate is in fact heterogeneous and also allow the gen-
eral documenting of route withdrawal.
So there has to be a way for AS2 to document this even if it does
not originate the route to 193.0.9.0/24 any more. This can be done
with the "withdrawn" attribute of the route object. The aggregate
route to 193.0.8.0/23 is now be registered as:
route: 193.0.8.0/23
descr: Enterprise 2
origin: AS2
...
With the two homogeneous routes marked as withdrawn from the Inter-
net routing mesh but still preserving their original routing infor-
mation.
route: 193.0.8.0/24
descr: Enterprise 2
origin: AS2
withdrawn: 940701
...
route: 193.0.9.0/24
descr: Enterprise 2 / Special
origin: AS2
comm-list: SPECIAL
withdrawn: 940701
...
It should be noted that the date value used in the withdrawn attri-
bute can only be in the past.
Proxy Aggregation
The next step of aggregation are aggregates consisting of more than
one AS. This generally means one AS is aggregating on behalf of
another. It is called proxy aggregation. Proxy aggregation should be
done with great care and always coordinates with other providers
announcing the same route.
Consider the following:
ripe-1nn.txt July, 1994
- 19 -
route: 193.0.0.0/20
descr: All routes known by AS1 in a single package
origin: AS1
...
route: 193.0.1.0/24
descr: Foo
origin: AS1
withdrawn: 940310
...
route: 193.0.8.0/24
descr: Bar
origin: AS2
withdrawn: 940310
...
route: 193.0.9.0/24
descr: Bar-2
origin: AS2
withdrawn: 940310
comm-list: SPECIAL
...
If AS1 announced no other routes to a single homed neighbouring AS,
that neighbour can in general either take that route or leave it but
not differentiate between AS1 and AS2.
Note: If the neighbor was previously configured to accept routes
originating in AS2 but not in AS1 they lose connectivity to AS2 as
well. This means that proxy aggregation has to be done carefully
and in a well coordinated fashion. The information in the withdrawn
route object can help to achieve that.
Aggregates with Holes
If we assume that the world of our example still consists of only
three chunks of address space the aggregate above contains what are
called holes, parts of an aggregate that are not reachable via the
originator of the route. From the routing information itself one
cannot tell whether these are holes and what part of the route falls
inside one. The only way to tell is to send a packet there and see
ripe-1nn.txt July, 1994
- 20 -
whether it gets to the destination, or an ICMP message is received
back, or there is silence. On the other hand announcing aggregates
with holes is quite legitimate. Consider a 16-bit aggregate with
only one 24-bit prefix unreachable. The savings in routing table
size by far outweigh the hole problem.
For operational reasons however it is very useful to register these
holes in the routing registry. Consider the case where a remote net-
work operator experiences connectivity problems to addresses inside
an aggregate route. If the packets are getting to the AS announcing
the aggregate and there are no more specific routes, the normal
cause of action is to get in touch with the originating AS of the
aggregate route and ask them to fix the problem. If the address
falls into a hole this is futile. Therefore problem diagnosis can be
sped up and unnecessary calls prevented by registering the holes in
the routing registry. We do this by using the "hole" attribute. In
our example the representation would be:
route: 193.0.0.0/20
descr: All routes known by AS1
origin: AS1
hole: 193.0.0.0/24
hole: 193.0.2.0/23
hole: 193.0.4.0/22
hole: 193.0.10.0/23
hole: 193.0.12.0/22
...
Note: there would also be two routes with the withdrawn attribute as
displayed above (i.e. 193.0.8.0/24 and 193.0.9.0/24)
Multiple Proxy Aggregation
Finally suppose that AS2 decides to announce the same aggregate,
they would add the following route object to the registry:
route: 193.0.0.0/20
descr: All routes known by AS2
origin: AS2
hole: 193.0.0.0/24
hole: 193.0.2.0/23
hole: 193.0.4.0/22
hole: 193.0.10.0/23
hole: 193.0.12.0/22
...
As per the update procedures below both AS1 and AS2 will be notified
that there already is a route to the same prefix in the registry.
This multiple proxy aggregation is very dangerous to do if the sub-
ripe-1nn.txt July, 1994
- 21 -
aggregates of the route are not the same. It is still dangerous when
the sub-aggregates are consistent but connectivity to the sub-
aggregates varies widely between the originators.
Route object update procedures
Adding a route object will be have to be authorised by the guardian
of the originating AS. The actual implementation of this is outside
the scope of this document. This guarantees that an AS guardian has
full control over the registration of the routes it announces.
What is an Inter-AS network ?
An inter-AS network(3) exists for the purpose of passing traffic and
routing information between different autonomous systems. The most
simple example of an inter-AS network is a point-to-point link, con-
necting exactly two ASes. Each end of such a link is connected to
an interface of router belonging to each of the autonomous systems.
More complex examples are broadcast type networks with multiple
interfaces connecting multiple ASes with the possibility of more
than one connection per AS. Consider the following example of three
routers 1, 2 and 3 with interfaces a through f connected by two
inter-AS networks X and Y:
X Y
a1b --- c2d --- e3f
Suppose that network X is registered in the routing registry as part
of AS1 and net Y as part of AS3. If traffic passes from left to
right prtraceroute will report the following sequence of interfaces
and ASes:
a in AS1
c in AS1
e in AS3
The traceroute algorithm enumerates only the receiving interfaces on
the way to the destination. In the example this leads to the pas-
sage of AS2 going unnoticed. This is confusing to the user and will
also generate exceptions when the path found is checked against the
routing registry.
_________________________
(3) Inter-AS IP networks are those networks are
currently called FIXes, IXFs, DMZs, NAPs, GIX and many
other acronyms.
ripe-1nn.txt July, 1994
- 22 -
For operational monitoring tools such as prtraceroute it is neces-
sary to know which interface on an inter-AS network belongs to which
AS. If AS information is not known about interfaces on an inter-AS
network, tools like prtraceroute cannot determine correctly which
ASes are being traversed.
All interfaces on inter-AS networks will are described in a separate
object know as the `inet-rtr' object [15].
ripe-1nn.txt July, 1994
- 23 -
6. The Autonomous System Object
Autonomous Systems
An Autonomous System (AS) is a group of IP networks run by one or
more network operators which has a single and clearly defined rout-
ing policy.
An AS has a unique number associated with it which is used both in
exchange of exterior routing information and as an identifier of the
AS itself. Exterior routing protocols such as BGP and EGP are used
to exchange routing information between ASes.
In routing terms an AS will normally use one or more interior gate-
way protocols (IGPs) in conjunction with some sort of common agreed
metrics when exchanging network information within its own AS.
The term AS is often confused or even misused as a convenient way of
grouping together a set of networks which belong under the same
administrative umbrella even if within that group of networks there
are various different routing policies. We provide the "community"
concept for such use. ASes can strictly have only one single rout-
ing policy.
The creation of an AS should be done in a conscious and well coordi-
nated manner to avoid creating ASes for the sake of it, perhaps
resulting in the worst case scenario of one AS per routing announce-
ment. It should be noted that there is a limited number of AS
numbers available. Also creating an AS may well increase the number
of AS paths modern EGPs will have to keep track of. This aggravates
what is known as "the routing table growth problem". This may mean
that by applying the general rules for the creation and allocation
of an AS below, some re-engineering may well be needed. However,
this may be the only way to actually implement the desired routing
policy anyway. The creation and allocation of an AS should be done
with the following recommendations in mind:
o Creation of an AS is only required when exchanging routing
information with other ASes. Some router implementations make
use of an AS number as a form of tagging to identify the rout-
ing process. However, it should be noted that this tag does
not need to be unique unless routing information is indeed
exchanged with other ASes.
o For a simple case of customer networks connected to a single
service provider, the IP network should normally be a member of
the service providers AS. In terms of routing policy the IP
network has exactly the same policy as the service provider and
there is no need to make any distinction in routing informa-
tion. This idea may at first seem slightly alien to some, but
it highlights the clear distinction in the use of the AS number
ripe-1nn.txt July, 1994
- 24 -
as a representation of routing policy as opposed to some form
of administrative use.
o If a network operator connects to more than one AS with dif-
ferent routing policies then they need to create their own AS.
In the case of multi-homed customer networks connected to two
service providers there are at least two different routing pol-
icies to a given customer network. At this point the customer
networks will be part of a single AS and this AS would be dis-
tinct from either of the service providers ASes. This allows
the customer the ability of having a different representation
of policy and preference to the different service providers.
This is the ONLY case where a network operator should create
its own AS number.
o As a general rule one should always try to populate the AS with
as many routes as possible, providing all routes conform to the
same routing policy.
Each AS is represented in the RIPE database by both an AS object and
the route objects representing the routes originated by the AS. The
AS object stores descriptive, administrative and contact information
about the AS as well as the routing policies of the AS in relation
to all neighbouring ASes.
The origin attributes of the route objects define the set of routes
originated by the AS. Each route object can have exactly one origin
attribute. Route objects can only be created and updated by the
"guardian" of the AS and not by those immediately responsible for
the particular routes referenced therein. This ensures that opera-
tors, especially service providers, remain in control of AS routing
announcements.
The AS object itself is used to represent a description of adminis-
trative details and the routing policies of the AS itself. The AS
object definition is depicted as follows.
ripe-1nn.txt July, 1994
- 25 -
Example:
aut-num: AS1104
descr: NIKHEF-H Autonomous system
as-in: from AS1213 100 accept AS1213
as-in: from AS1913 100 accept AS1913
as-in: from AS1755 150 accept ANY
as-out: to AS1213 announce ANY
as-out: to AS1913 announce ANY
as-out: to AS1755 announce AS1104 AS1913 AS1213
tech-c: Rob Blokzijl
admin-c: Eric Wassenaar
guardian: as-guardian(a)nikhef.nl
changed: ripe-dbm(a)ripe.net 920910
source: RIPE
See Appendix A for a complete syntax definition of the "aut-num"
object.
It should be noted that this representation provides two things:
o a set of routes.
o a description of administrative details and routing policies.
The set of routes can be used to generate network list based confi-
guration information as well as configuration information for exte-
rior routing protocols knowing about ASes. This means an AS can be
defined and is useful even if it does not use routing protocols
which know about the AS concept.
ripe-1nn.txt July, 1994
- 26 -
Description of local connections between ASes - "interas-
in/interas-out".
Description of local connections between ASes is necessary only if
the ASes are connected by more than one link and routing policy
differs between the two links. These local differences are visible
only to the two ASes concerned and not beyond them.
Note: The description of local connections is applicable
only to very few configurations. The tutorial description
below is less detailed than other parts of this document.
Those interested but not experienced should contact their
routing registry for support.
Often two ASes will have more than one physical connection between
them. In practice certain local policies my be placed on these
inter-AS connections as agreed by the two ASes. If we look at the
example of two ASes, AS2 and AS3 connected with links 193.0.1.1-
193.0.1.2 and 193.0.1.5-193.0.1.6:
Example:
LINK1
193.0.1.1 +----------+ 193.0.1.2
| |
AS1------AS2== ==AS3-----AS4
| |
193.0.1.5 +----------+ 193.0.1.6
LINK2
It may be that AS2 wants to use LINK2 only for traffic towards AS4.
LINK1 is used for traffic to AS3 and as backup to AS4, should LINK2
fail. While this is purely of local information and at the AS level
will have no significance per se to any other ASes except AS2 and
AS3 this may be useful to represent. The way this is done is by
using the attributes "interas-in" and "interas-out". The exact syn-
tax is given in Appendix A. However, if we follow this example
through in terms of AS2 we would represent this policy as follows:
Example:
aut-num: AS2
as-in: from AS3 10 accept AS3 AS4
as-out: to AS3 announce AS1 AS2
interas-in: from AS3 193.0.1.1/32 193.0.1.2/32 (pref-type=5) accept AS3
interas-in: from AS3 193.0.1.1/32 193.0.1.2/32 (pref-type=15) accept AS4
interas-in: from AS3 193.0.1.5/32 193.0.1.6/32 (pref-type=10) accept AS4
...
ripe-1nn.txt July, 1994
- 27 -
Here we see additional local link based information in terms of the
IP addresses of the link. It should be noted that the preference on
interas-in attributes is only of relevance to other interas-in
attributes in the same AS and not to as-in or default attribute.
The parentheses and keyword are syntactic sugar to allow further
extensions. If pref-type=MED is specified the preference indicated
by the remote as via the multi-exit discriminator metric of BGP is
used. Of course this type on inter-AS policy should always be bila-
terally agreed to avoid asymmetry and in practice there may need to
be corresponding interas-in attributes in the policy representation
of AS3.
The interas-out attribute is similar in the same way to interas-in
as as-out to as-in. The one major difference being that interas-out
allows to associate an outgoing metric with each route. It is impor-
tant to note that this metric is just passed to the peer AS and it
is at the peer AS's discretion to use or ignore it. A special value
of IGP specifies that the metric passed to the receiving AS will be
derived from the IGP of the sending AS. In this way the peer AS can
choose the optimal link for its traffic as determined by the sending
AS.
Descriptions of local policies do not replace the global policy
described in as-in, as-out and other policy attributes which should
be specified too. If the global policy mentions more routes than
the local policy then local preferences for these routes are assumed
to be equal for all links. If a route is only referenced in some
interas-in/out attributes and not in others it is assumed not
announced/accepted on the links concerned (see the example above).
The key difference between interas-in/interas-out and as-in/as-in
attributes is the former describes a local inter-AS policy and the
latter the general inter-AS policy as seen by other ASes. The gen-
eral policy should always be defined. The local inter-AS policy
should only be defined when such a policy really exists and the
implications of setting such policies is fully understood.
ripe-1nn.txt July, 1994
- 28 -
How to describe the exclusion policy of a certain AS - "as-exclude"
Some ASes have a routing policy based on the exclusion of certain
routes if for whatever reason a certain AS is used as transit.
Whilst, this is in general not good practice as it makes implicit
assumptions on topology with asymmetry a possible outcome if not
coordinated, this case needs to be accommodated within the routing
policy representation.
The way this is achieved is by making use of the "as-exclude" attri-
bute. The precise syntax of this attribute can be found in Appendix
A along with the rest of the defined syntax for the "aut-num"
object. However, some explanation of the use of this attribute is
useful. If we have the following example topology.
Example:
AS4--------AS3
| | |
| | |
AS1--------AS2--------AS5
With a simple corresponding policy like so:
Example:
aut-num: AS1
as-in: from AS2 100 accept ANY
as-out: to AS2 announce AS1
as-exclude: exclude AS4 to ANY
....
We see an interesting policy. What this says in simple terms is AS1
doesn't want to reach anything if it transit AS4. This can be a per-
fectly valid policy. However, it should be realised that for what-
ever reason AS2 decides to route to AS3 via AS4 then immediately AS1
has no connectivity to AS3 or if AS1 is running default to AS2 pack-
ets from AS1 will still flow via AS4. The important point about this
is that whilst AS1 can advise its neighbours of its policy it has no
direct control on how it can enforce this policy to neighbours
upstream.
Another interesting scenario to highlight the unexpected result of
using such an "as-exclude" policy. If we assume in the above example
AS2 preferred AS4 to reach AS3 and AS1 did not use default routing
then as stated AS1 would have no connectivity to AS3. Now lets sup-
pose that for example the link between AS2 and AS4 went down for
some reason. Like so:
ripe-1nn.txt July, 1994
- 29 -
Example:
AS4--------AS3
|
|
AS1--------AS2--------AS5
Suddenly AS1 now has connectivity to AS3. This unexpected behavior
should be considered when created policies based on the "as-exclude"
attribute.
The second problem with this type of policy is the potential of
asymmetry. In the original example we saw the correct policy from
AS1's point of view but if ASes with connectivity through AS4 do not
use a similar policy you have asymmetric traffic and policy. If an
AS uses such a policy they must be aware of the consequences of its
use. Namely that the specified routes which transit the AS (i.e.
routing announcements with this AS in the AS path information) in
question will be excluded. If not coordinated this can easily cause
asymmetry or even worse loss of connectivity to unknown ASes behind
(or in front for that matter) the transit AS in question. With this
in mind this attribute can only be viewed as a form of advisory to
other service providers. However, this does not preclude its use
with policy based tools if the attribute exists.
By having the ability to specify a route keyword based on any of the
four notations given in the syntax it allows the receiving AS to
specify what routes it wishes to exclude through a given transit AS
to a network granularity.
ripe-1nn.txt July, 1994
- 30 -
7. AS Macros
It may be difficult to keep track of each and every new AS that is
represented in the routing registry. A convenient way around this
is to define an `AS Macro' which essentially is a convenient way to
group ASes. This is done so that each and every AS guardian does not
have to add a new AS to it's routing policy as described by the as-
in and as-out attributes of it's AS object.
However, it should be noted that this creates an implicit trust on
the guardian of the AS-Macro.
An AS-Macro can be used in <routing policy expressions> for the
"as-in" and "as-out" attributes in the aut-num object. The AS-Macro
object is then used to derive the list or group of ASes.
A simple example would be something like:
Example:
aut-num: AS786
as-in: from AS1755 100 accept AS-EBONE AND NOT AS1104
as-in: from AS1755 100 accept AS-EBONE AND NOT AS1104
as-out to AS1755 announce AS786
.....
Where the as-macro object for AS-EBONE is as follows:
as-macro: AS-EBONE
descr: ASes routed by EBONE
as-list: AS2121 AS1104 AS2600 AS2122
as-list: AS1103 AS1755 AS2043
guardian: guardian(a)ebone.net
......
So the policy would be evaluated to:
aut-num: AS786
as-in: from AS1755 100 accept (AS2121 OR AS1104 OR AS2600 OR AS2122
as-in: from AS1755 100 accept AS1103 OR AS1755 OR AS2043) AND NOT AS1104
......
It should be noted that the above examples incorporates the rule for
line wrapping as defined in Appendix A for policy lines. See Appen-
dix C for a definition on the AS-Macro syntax.
ripe-1nn.txt July, 1994
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8. The Community Object
A community is a group of routes that cannot be represented by an AS
or a group of ASes. It is in some circumstances useful to define a
group of routes that have something in common. This could be a spe-
cial access policy to a supercomputer centre, a group of routes used
for a specific mission, or a disciplinary group that is scattered
among several autonomous systems. Also these communities could be
useful to group routes for the purpose of network statistics.
Communities do not exchange routing information, since they do not
represent an autonomous system. More specifically, communities do
not define routing policies, but access or usage policies. However,
they can de used as in conjunction with an ASes routing policy to
define a set of routes the AS sets routing policy for.
Communities should be defined in a strict manner, to avoid creating
as many communities as there are routes, or even worse. Communities
should be defined following the two rules below;
o Communities must have a global meaning. Communities that have
no global meaning, are used only in a local environment and
should be avoided.
o Communities must not be defined to express non-local policies.
It should be avoided that a community is created because some
other organisation forces a policy upon your organisation.
Communities must only be defined to express a policy defined by
your organisation.
Community examples
There are some clear examples of communities:
BACKBONE -
all customers of a given backbone service provider even though
they can have various different routing policies and hence
belong to different ASes. This would be extremely useful for
statistics collection.
HEPNET -
the High Energy Physics community partly shares infrastructure
with other organisations, and the institutes it consists of are
scattered all over Europe, often being part of a non HEPNET
autonomous system. To allow statistics, access or part of a
routing policy , a community HEPNET, consisting of all routes
that are part of HEPNET, conveniently groups all these routes.
ripe-1nn.txt July, 1994
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NSFNET -
the National Science Foundation Network imposes an acceptable
use policy on routes that wish to make use of it. A community
NSFNET could imply the set of routes that comply with this pol-
icy.
MULTI -
a large multinational corporation that does not have its own
internal infrastructure, but connects to the various parts of
its organisations by using local service providers that connect
them all together, may decide to define a community to restrict
access to their networks, only by networks that are part of
this community. This way a corporate network could be defined
on shared infrastructure. Also, this community could be used by
any of the service providers to do statistics for the whole of
the corporation, for instance to do topology or bandwidth plan-
ning.
Similar to Autonomous systems, each community is represented in the
RIPE database by both a community object and community tags on the
route objects representing the routes belonging to the community.
The community object stores descriptive, administrative and contact
information about the community.
The community tags on the route objects define the set of routes
belonging to a community. A route can have multiple community tags.
The community tags can only be created and updated by the "guardian"
of the community and not by those directly responsible for the par-
ticular network. This ensures that guardians remain in control of
community membership.
Here's an example of how this might be represented in terms of the
community tags within the network object. We have an example where
the route 192.16.199.0/24 has a single routing policy (i.e. that of
AS 1104), but is part of several different communities of interest.
We use the tag "comm-list" to represent the list of communities
associated with this route. NIKHEF-H uses the service provider
SURFNET (a service provider with customers with more than one rout-
ing policy), is also part of the High Energy Physics community as
well as having the ability to access the Supercomputer at CERN(4).
_________________________
(4) The community `CERN-SUPER', is somewhat national,
but is intended as an example of a possible use of an
access policy constraint.
ripe-1nn.txt July, 1994
- 33 -
Example:
route: 192.16.199.0/24
descr: Local Ethernet
descr: NIKHEF section H
origin: AS1104
comm-list: HEPNET CERN-SUPER SURFNET
changed: ripe-dbm(a)ripe.net 920604
source: RIPE
In the above examples some communities have been defined. The com-
munity object itself will take the following format:
Example:
community: SURFNET
descr: Dutch academic research network
authority: SURFnet B.V.
guardian: comm-guardian(a)surfnet.nl
admin-c: Erik-Jan Bos
tech-c: Erik-Jan Bos
changed: ripe-dbm(a)ripe.net 920604
source: RIPE
For a complete explanation of the syntax please refer to Appendix B.
ripe-1nn.txt July, 1994
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9. Representation of Routing Policies
Routing policies of an AS are represented in the autonomous system
object. Initially we show some examples, so the reader is familiar
with the concept of how routing information is represented, used and
derived. Refer to Appendix A, for the full syntax of the "aut-num"
object.
The topology of routing exchanges is represented by listing how
routing information is exchanged with each neighbouring AS. This is
done separately for both incoming and outgoing routing information.
In order to provide backup and back door paths a relative cost is
associated with incoming routing information.
Example 1:
AS1------AS2
This specifies a simple routing exchange of two presumably isolated
ASes. Even if either of them has routing information about routes
in ASes other than AS1 and AS2, none of that will be announced to
the other.
aut-num: AS1
as-out: to AS2 announce AS1
as-in: from AS2 100 accept AS2
aut-num: AS2
as-out: to AS1 announce AS2
as-in: from AS1 100 accept AS1
The number 100 in the in-bound specifications is a relative cost,
which is used for backup and back door routes. The absolute value is
of no significance. The relation between different values within the
same AS object is. A lower value means a lower cost. This is cons-
ciously similar to the cost based preference scheme used with DNS MX
RRs.
Example 2:
Now suppose that AS2 is connected to one more AS, besides AS1, and
let's call that AS3:
AS1------AS2------AS3
ripe-1nn.txt July, 1994
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In this case there are two reasonable routing policies:
a) AS2 just wants to exchange traffic with both AS1 and AS3 itself
without passing traffic between AS1 and AS3.
b) AS2 is willing to pass traffic between AS3 and AS1, thus acting
as a transit AS
Example 2a:
In the first case AS1's representation in the routing registry will
remain unchanged as will be the part of AS2's representation
describing the routing exchange with AS1. A description of the addi-
tional routing exchange with AS3 will be added to AS2's representa-
tion:
aut-num: AS1
as-out: to AS2 announce AS1
as-in: from AS2 100 accept AS2
aut-num: AS2
as-out: to AS1 announce AS2
as-in: from AS1 100 accept AS1
as-out: to AS3 announce AS2
as-in: from AS3 100 accept AS3
aut-num: AS3
as-out: to AS2 announce AS3
as-in: from AS2 100 accept AS2
Note that in this example, AS2 keeps full control over its
resources. Even if AS3 and AS1 were to allow each others routes in
from AS2, the routing information would not flow because AS2 is not
announcing it(5).
Example 2b:
If contrary to the previous case, AS1 and AS3 are supposed to have
connectivity to each other via AS2, all AS objects have to change:
_________________________
(5) Of course AS1 and AS3 could just send traffic to
each other to AS2 even without AS2 announcing the
routes, hoping that AS2 will forward it correctly. Such
questionable practices however are beyond the scope of
this document.
ripe-1nn.txt July, 1994
- 36 -
aut-num: AS1
as-out: to AS2 announce AS1
as-in: from AS2 100 accept AS2 AS3
aut-num: AS2
as-out: to AS1 announce AS2 AS3
as-in: from AS1 100 accept AS1
as-out: to AS3 announce AS2 AS1
as-in: from AS3 100 accept AS3
aut-num: AS3
as-out: to AS2 announce AS3
as-in: from AS2 100 accept AS1 AS2
Note that the amount of routing information exchanged with a neigh-
bour AS is defined in terms of routes belonging to ASes. In BGP
terms this is the AS where the routing information originates and
the originating AS information carried in BGP could be used to
implement the desired policy. However, using BGP or the BGP AS-path
information is not required to implement the policies thus speci-
fied. Configurations based on route lists can easily be generated
from the database. The AS path information, provided by BGP can
then be used as an additional checking tool as desired.
The specification understands one special expression and this can be
expressed as a boolean expressions:
ANY - means any routing information known. For output this means
that all routes an AS knows about are announced. For input it
means that anything is accepted from the neighbour AS.
ripe-1nn.txt July, 1994
- 37 -
Example 3:
AS4 is a stub customer AS, which only talks to service provider
AS123.
|
|
-----AS123------AS4
|
|
aut-num: AS4
as-out: to AS123 announce AS4
as-in: from AS123 100 accept ANY
aut-num: AS123
as-in: from AS4 100 accept AS4
as-out: to AS4 announce ANY
<further neighbours>
Since AS4 has no other way to reach the outside world than AS123 it
is not strictly necessary for AS123 to send routing information to
AS4. AS4 can simply send all traffic for which it has no explicit
routing information to AS123 by default. This strategy is called
default routing. It is expressed in the routing registry by adding
one or more default tags to the autonomous system which uses this
strategy. In the example above this would look like:
aut-num: AS4
as-out: to AS123 announce AS4
default: AS123 100
aut-num: AS123
as-in: from AS4 100 accept AS4
<further neighbours>
ripe-1nn.txt July, 1994
- 38 -
Example 4:
AS4 now connects to a different operator, AS5. AS5 uses AS123 for
outside connectivity but has itself no direct connection to AS123.
AS5 traffic to and from AS123 thus has to pass AS4. AS4 agrees to
act as a transit AS for this traffic.
|
|
-----AS123------AS4-------AS5
|
|
aut-num: AS4
as-out: to AS123 announce AS4 AS5
as-in: from AS123 100 accept ANY
as-out: to AS5 announce ANY
as-in: from AS5 50 accept AS5
aut-num: AS5
as-in: from AS4 100 accept ANY
as-out: to AS4 announce AS5
aut-num: AS123
as-in: from AS4 100 accept AS4 AS5
as-out: to AS4 announce ANY
<further neighbours>
Now AS4 has two sources of external routing information. AS5 which
provides only information about its own routes and AS123 which pro-
vides information about the external world. Note that AS4 accepts
information about AS5 from both AS123 and AS5 although AS5 informa-
tion cannot come from AS123 since AS5 is connected only via AS4
itself. The lower cost of 50 for the announcement from AS5 itself
compared to 100 from AS123 ensures that AS5 is still believed even
in case AS123 will unexpectedly announce AS5.
In this example too, default routing can be used by AS5 much like in
the previous example. AS4 can also use default routing towards
AS123:
ripe-1nn.txt July, 1994
- 39 -
aut-num: AS4
as-out: to AS123 announce AS4 AS5
default: AS123 11
as-in: from AS5 50 accept AS5
Note no announcements to AS5, they default to us.
aut-num: AS5
as-out: to AS4 announce AS5
default: AS4 100
aut-num: AS123
as-in: from AS4 100 announce AS4 AS5
<further neighbours>
Note that the relative cost associated with default routing is
totally separate from the relative cost associated with in-bound
announcements. The default route will never be taken if an explicit
route is known to the destination. Thus an explicit route can never
have a higher cost than the default route. The relative cost asso-
ciated with the default route is only useful in those cases where
one wants to configure multiple default routes for redundancy.
Note also that in this example the configuration using default
routes has a subtly different behavior than the one with explicit
routes: In case the AS4-AS5 link fails AS4 will send traffic to AS5
to AS123 when using the default configuration. Normally this makes
not much difference as there will be no answer and thus little
traffic. With certain datagram applications which do not require
acknowledgments however, significant amounts of traffic may be use-
lessly directed at AS123. Similarly default routing should not be
used if there are stringent security policies which proscribe any
traffic intended for AS5 to ever touch AS123.
Generally it can be said that default routing should only be used in
very simple topologies. Once the situation gets more complex using
default routes can lead to unexpected results or even defeat the
routing policies established when links fail. As an example consider
how Example 5a) below could be implemented using default routing.
ripe-1nn.txt July, 1994
- 40 -
Example 5:
In a different example AS4 has a private connection to AS6 which in
turn is connected to the service provider AS123:
|
|
-----AS123------AS4
| |
| |
| |
AS6 ---------+
There are a number of policies worth examining in this case:
a) AS4 and AS6 wish to exchange traffic between themselves
exclusively via the private link between themselves; such
traffic should never pass through the backbone (AS123). The
link should never be used for transit traffic, i.e. traffic not
both originating in and destined for AS4 and AS6.
b) AS4 and AS6 wish to exchange traffic between themselves via the
private link between themselves. Should the link fail, traffic
between AS4 and AS6 should be routed via AS123. The link
should never be used for transit traffic.
c) AS4 and AS6 wish to exchange traffic between themselves via the
private link between themselves. Should the link fail, traffic
between AS4 and AS6 should be routed via AS123. Should the
connection between AS4 and AS123 fail, traffic from AS4 to des-
tinations behind AS123 can pass through the private link and
AS6's connection to AS123.
d) AS4 and AS6 wish to exchange traffic between themselves via the
private link between themselves. Should the link fail, traffic
between AS4 and AS6 should be routed via AS123. Should the
backbone connection of either AS4 or AS6 fail, the traffic of
the disconnected AS should flow via the other AS's backbone
connection.
ripe-1nn.txt July, 1994
- 41 -
Example 5a:
aut-num: AS4
as-in: from AS123 100 accept NOT AS6
as-out: to AS123 announce AS4
as-in: from AS6 50 accept AS6
as-out: to AS6 announce AS4
aut-num: AS123
as-in: from AS4 100 accept AS4
as-out: to AS4 announce ANY
as-in: from AS6 100 accept AS6
as-out: to AS6 announce ANY
<further neighbours>
aut-num: AS6
as-in: from AS123 100 accept NOT AS4
as-out: to AS123 announce AS6
as-in: from AS4 50 accept AS4
as-out: to AS4 announce AS6
Note that here the configuration is slightly inconsistent. AS123
will announce AS6 to AS4 and AS4 to AS6. These announcements will be
filtered out on the receiving end. This will implement the desired
policy. Consistency checking tools might flag these cases however.
ripe-1nn.txt July, 1994
- 42 -
Example 5b:
aut-num: AS4
as-in: from AS123 100 accept ANY
as-out: to AS123 announce AS4
as-in: from AS6 50 accept AS6
as-out: AS6 AS4
aut-num: AS123
as-in: AS4 100 AS4
as-out: AS4 ANY
as-in: AS6 100 AS6
as-out: AS6 ANY
<further neighbours>
aut-num: AS6
as-in: from AS123 100 accept ANY
as-out: to AS123 announce AS6
as-in: from AS4 50 accept AS4
as-out: to AS4 announce AS6
The thing to note here is that in the ideal operational case, `all
links working' AS4 will receive announcements for AS6 from both
AS123 and AS6 itself. In this case the announcement from AS6 will
be preferred because of its lower cost and thus the private link
will be used as desired. AS6 is configured as a mirror image.
ripe-1nn.txt July, 1994
- 43 -
Example 5c:
The new feature here is that should the connection between AS4 and
AS123 fail, traffic from AS4 to destinations behind AS123 can pass
through the private link and AS6's connection to AS123.
aut-num: AS4
as-in: from AS123 100 accept ANY
as-out: to AS123 announce AS4
as-in: from AS6 50 accept AS6
as-in: from AS6 110 accept ANY
as-out: to AS6 AS4
aut-num: AS123
as-in: from AS4 1 accept AS4
as-out: to AS4 announce ANY
as-in: from AS6 1 accept AS6
as-in: from AS6 2 accept AS4
as-out: to AS6 announce ANY
<further neighbours>
aut-num: AS6
as-in: from AS123 100 accept ANY
as-out: to AS123 AS6 announce AS4
as-in: from AS4 50 accept AS4
as-out: to AS4 announce ANY
Note that it is important to make sure to propagate routing informa-
tion for both directions in backup situations like this. Connec-
tivity in just one direction is not useful at all for almost all
applications.
Note also that in case the AS6-AS123 connection breaks, AS6 will
only be able to talk to AS4. The symmetrical case (5d) is left as an
exercise to the reader.
10. Future Extensions
We envision that over time the requirements for describing routing
policy will evolve. The routing protocols will evolve to support the
requirements and the routing policy description syntax will need to
evolve as well. For that purpose, a separate document will describe
experimental syntax definitions for policy description. This docu-
ment will be updated when new objects or attributes are proposed or
modified.
Two new attributes of the AS object which are proposed and supported
by the Merit Routing Registry are as-transit and db-selector.
as-transit describes the transit preferences of an AS. It allows an
AS to describe its path preference in order to reach certain
ripe-1nn.txt July, 1994
- 44 -
destinations. The AS(s) specified in the path preference may or may
not be an immediate neighbor of the AS defined in the AS object.
as-transit accommodates policy decisions involving AS path whereas
as-in and as-out do not. It is not unusual for ASs to have routing
policies which involve path selection based on AS. Emerging proto-
cols like SDRP [13] will allow an AS to choose a path independent of
a neighboring ASs path choice. as-transit permits descriptions based
on AS path selection.
The DataBase Selector (db-selector) function allows one to take
advantage of information registered in other Registries. It permits
the selection of networks in a database based on their attributes.
It is proposed to be used within the as-in/as-out attribute family
to make the description of policy concise. For example, if an AS
has the policy of not accepting any routes from country XYZ, the AS
can use the db-selector to check a database which has a network and
country attribute and relate that information to the information in
the routing registry. The advantage of referencing another database
is that the routing registry will avoid duplicating the information
maintained in other information registries.
Detailed examples and syntax are described in document ???? [14].
ripe-1nn.txt July, 1994
- 45 -
11. References
[1] Bates, T., Jouanigot, J-M., Karrenberg, D., Lothberg, P.,
Terpstra, M., "Representation of IP Routing Policies in the
RIPE Database", RIPE-81, February 1993.
[2] Merit Network Inc.,"Representation of Complex Routing Policies
of an Autonomous System", DRAFT, March, 1994.
[3] PRIDE Tools Release 1.
See ftp.ripe.net:pride/tools/pride-tools-1.tar.Z.
[4] Merit Inc. RRDB Tools.
See rrdb.merit.edu:pub/meritrr/*
[5] The Network List Compiler.
See dxcoms.cern.ch:pub/ripe-routing-wg/nlc-2.2d.tar
[6] Lord, A., Terpstra, M., "RIPE Database Template for Networks
and Persons", DRAFT, May 1994.
[7] Karrenberg, D., "RIPE Database Template for Domains", RIPE-49,
April 1992.
[8] Lougheed, K., Rekhter, Y., "A Border Gateway Protocol 3 (BGP-
3)", RFC1267, October 1991.
[9] Rekhter, Y., Li, T., "A Border Gateway Protocol 4 (BGP-4)",
RFC-1654, May 1994.
[10] Bates, T., Karrenberg, D., Terpstra, M., "Support for Classless
Internet Addresses in the RIPE Database", DRAFT, May 1994.
[11] Karrenberg, D., "Authorisation and Notification of Changes in
the RIPE Database", RIPE-96, October 1993.
[12] Bates, T., "Support of Guarded fields within the RIPE Data-
base", ripe-108, February 1994.
[13] Estrin, D., Li, T., Rekhter, Y., Varadhan, K., "Source Demand
Routing: Packet Format and Forwarding Specification (Version
1)", INTERNET-DRAFT, draft-ietf-sdr-sdrp-04.txt, March 1994.
[14] ?????, "Experimental Objects and attributes for the Routing
Registry, ???, ????.
[15] Bates, T., "Specifying an `Internet Router' in the Routing
Registry", DRAFT, July 1994.
ripe-1nn.txt July, 1994
- 46 -
12. Author's Addresses
Tony Bates
RARE/PRIDE Project
c/o RIPE Network Coordination Centre
Kruislaan 409
NL-1098 SJ Amsterdam
The Netherlands
+31 20 592 5064
T.Bates(a)ripe.net
Elise Gerich
The University of Michigan
Merit Computer Network
1075 Beal Avenue
Ann Arbor, MI 48109
USA
+1 313 936 2120
epg(a)merit.edu
Laurent Joncheray
The University of Michigan
Merit Computer Network
1075 Beal Avenue
Ann Arbor, MI 48109
USA
+1 313 936 2065
lpj(a)merit.edu
Jean-Michel Jouanigot
CERN, European Laboratory for Particle Physics
CH-1211 Geneva 23
Switzerland
+41 22 767 4417
Jean-Michel.Jouanigot(a)cern.ch
Daniel Karrenberg
RIPE Network Coordination Centre
Kruislaan 409
NL-1098 SJ Amsterdam
The Netherlands
+31 20 592 5065
D.Karrenberg(a)ripe.net
ripe-1nn.txt July, 1994
- 47 -
Marten Terpstra
PRIDE Project
c/o RIPE Network Coordination Centre
Kruislaan 409
NL-1098 SJ Amsterdam
The Netherlands
+31 20 592 5064
M.Terpstra(a)ripe.net
Jessica Yu
The University of Michigan
Merit Computer Network
1075 Beal Avenue
Ann Arbor, MI 48109
USA
+1 313 936 2655
jyy(a)merit.edu
ripe-1nn.txt July, 1994
- 48 -
Appendix A - Syntax for the aut-num object.
Here is a summary of the tags associated with aut-num object itself
and their status. The first column specifies the attribute, the
second column whether this attribute is mandatory in the aut-num
object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
aut-num: [mandatory] [single]
descr: [mandatory] [multiple]
as-in: [optional] [multiple]
as-out: [optional] [multiple]
interas-in: [optional] [multiple]
interas-out: [optional] [multiple]
as-exclude: [optional] [multiple]
default: [optional] [multiple]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
guardian: [mandatory] [single]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
aut-num:
The autonomous system number. This must be a uniquely allo-
cated autonomous system number from an AS registry (i.e. the
RIPE NCC, the Inter-NIC, etc).
Format:
AS<positive integer between 1 and 65535>
Example:
aut-num: AS1104
Status: mandatory, only one line allowed
descr:
A short description of the Autonomous System.
Format:
free text
Status: mandatory, multiple lines allowed
as-in:
ripe-1nn.txt July, 1994
- 49 -
Example:
descr: NIKHEF section H
descr: Science Park Watergraafsmeer
descr: Amsterdam
A description of accepted routing information between AS peers.
Format:
from <aut-num> <cost> accept <routing policy expression>
The keywords from and accept are optional and can be omit-
ted.
<aut-num> refers to your AS neighbour.
<cost> is a positive integer used to express a relative
cost of routes learned. The lower the cost the more pre-
ferred the route.
<routing policy expression> can take the following for-
mats.
1. A list of one or more ASes, AS Macros, Communities or
Network Lists.
A Network List is a list of network numbers in prefix
length format, separated by commas, and surrounded by
curly brackets.
Examples:
as-in: from AS1103 100 accept AS1103
as-in: from AS786 105 accept AS1103
as-in: from AS786 10 accept AS786 HEPNET
as-in: from AS1755 110 accept AS1103 AS786
as-in: from AS3333 100 accept {192.87.45.0/16, 128.141.0.0/16}
2. A set of KEYWORDS. The following KEYWORD is
currently defined:
ANY this means anything the neighbour AS knows.
3. A logical expression of either 1 or 2 above The
current logical operators are defined as:
AND
OR
NOT
ripe-1nn.txt July, 1994
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NOTE: if no logical operator is given between ASes,
AS-macros, Communities, Network Lists and KEYWORDS it
is implicitly evaluated as an `OR' operation. The OR
can be left out for conciseness.
Rules are grouped together using parenthesis i.e "("
and ")".
Example:
as-in: from AS1755 100 accept ANY AND NOT (AS1234 OR AS513)
as-in: from AS1755 150 accept AS1234 OR {35.0.0.0/8}
A rule can be wrapped over lines providing the
associated <aut-num>, <cost> values and from and
accept keywords are repeated and occur on con-
secutive lines.
Example:
as-in: from AS1755 100 accept ANY AND NOT (AS1234 AS513)
and
as-in: from AS1755 100 accept ANY AND NOT (
as-in: from AS1755 100 accept AS1234 AS513)
are evaluated to the same result. Please note
that the ordering of these continuing lines
matters.
Status: optional, multiple lines allowed
as-out:
A description of generated routing information sent to other AS
peers.
Format:
to <aut-num> announce <routing policy expression
The to and announce keywords are optional and can be omit-
ted.
<aut-num> refers to your AS neighbour.
<routing policy expression> is explained in the as-in
attribute definition above.
Example:
as-out: to AS1104 announce AS978
as-out: to AS1755 announce ANY
as-out: to AS786 announce ANY AND NOT (AS978)
Status: optional, multiple lines allowed
ripe-1nn.txt July, 1994
- 51 -
interas-in:
Describes incoming local preferences on an inter AS connection.
Format:
from <aut-num> <local-info> <pref> accept <routing policy
expression>
The keywords from and accept are optional and can be omit-
ted.
<aut-num> is an autonomous system as defined in as-in.
<local-info> contains the IP address of the local border
router, followed by a space, followed by the IP address of
the remote border router. IP addresses must be in prefix
length format.
<pref> is defined as follows:
(pref-type=<value>)
It should be noted the parenthesis ``('' and ``)'' and the
``pref-type'' keyword must be present for this preference
to be valid.
<value> can take one of the following values:
<cost>
<cost> is a positive integer used to express a rela-
tive cost of routes learned. The lower the cost the
more preferred the route. This <cost> value is only
relevant to other interas-in attributes, not to as-in
attributes.
MED
This indicates the AS will use the BGP MED metric
sent from its neighbour AS.
NOTE: Combinations of MED and <cost> should be
avoided for the same destinations.
CAVEAT: The pref-type values may well be enhanced in
the future as more inter-ASs routing protocols intro-
duce other metrics.
<routing policy expression> is an expression as defined in
as-in above.
Examples:
interas-in: from AS1104 192.87.45.254/32 192.87.45.80/32 (pref-type=10) accept AS786 AS987
interas-in: from AS1104 192.87.45.254/32 192.87.45.79/32 (pref-type=20) accept AS987
interas-in: from AS1103 192.87.45.254/32 192.87.45.32/32 (pref-type=MED) accept ANY
Status: optional, multiple lines allowed
ripe-1nn.txt July, 1994
- 52 -
interas-out:
Format:
to <aut-num> <local-info> announce <metric> <routing pol-
icy expression>
The keywords to and announce are optional and can be omit-
ted.
The definitions of <aut-num>, <local-info>, and <routing
policy expression> are identical to those defined in
interas-in.
<metric> is defined as follows:
(metric-out=<value>)
It should be noted the parenthesis ``('' and ``)'' and the
``metric-out'' keyword must be present for this metric to
be valid.
<value> can take one of the following values:
<num-metric>
<num-metric> is a pre-configured metric for outbound
routes. The lower the cost the more preferred the
route. This <num-metric> value is only relevant to
other interas-out attributes, not to as-out attri-
butes.
IGP
This indicates that this means that the metric
reflects the ASs internal topology cost. The topology
is reflected here by using MED which is derived from
the AS's IGP metric.
NOTE: Combinations of IGP and <num-metric> should be
avoided for the same destinations.
CAVEAT: The metric-out values may well be enhanced in
the future as more interas protocols make use of
metrics.
Examples:
interas-out: to AS1104 192.87.45.254/32 192.87.45.80/32 (metric-out=10) announce AS23 AS10
interas-out: to AS1104 192.87.45.254/32 192.87.45.79/32 (metric-out=15) announce AS10
interas-out: to AS1103 192.87.45.254/32 192.87.45.79/32 (metric-out=IGP) announce ANY
Status: optional, multiple lines allowed
as-exclude:
A list of transit ASes to ignore all routes from.
ripe-1nn.txt July, 1994
- 53 -
Format:
exclude <aut-num> to <exclude-route-keyword>
Keywords exclude and to are optional and can again be
omitted.
<aut-num> refers to the transit AS in question.
an <exclude-route-keyword> can be ONE of the following.
1. <aut-num>
2. AS macro
3. Community
4. ANY
Examples:
as-exclude: exclude AS690 to HEPNET
This means exclude any HEPNET routes which have a route
via AS690.
as-exclude: exclude AS1800 to AS-EUNET
This means exclude any AS-EUNET routes which have a route
via AS1800.
as-exclude: exclude AS1755 to AS1104
This means exclude any AS1104 route which have a route via
AS1755.
as-exclude: exclude AS1104 to ANY
This means exclude all routes which have a route via
AS1104.
Status: optional, multiple lines allowed
default:
An indication of how default routing is done.
Format:
<aut-num> <relative cost> <default-expression>
where <aut-num> is the AS peer you will default route to,
and <relative cost> is the relative cost is a positive
integer used to express a preference for default. There is
no relationship to the cost used in the as-in tag. The AS
peer with the lowest cost is used for default over ones
ripe-1nn.txt July, 1994
- 54 -
with higher costs.
<default-expression> is optional and provides information
on how a default route is selected. It can take the fol-
lowing formats:
1. static. This indicates that a default is statically
configured to this AS peer.
2. A network list with the syntax as described in the
as-in attribute. This indicates that this list of
routes is used to generate a default route. A special
but valid value in this is the special route used by
some routing protocols to indicate default: 0.0.0.0/0
3. default. This is the same as {0.0.0.0/0}. This means
that the routing protocol between these two peers
generates a true default.
Examples:
default: AS1755 10
default: AS786 5 {140.222.0.0/16, 192.87.45.0/24}
default: AS2043 15 default
Status: optional, multiple lines allowed
tech-c:
Full name or uniquely assigned NIC-handle of a technical con-
tact person. This is someone to be contacted for technical
problems such as misconfiguration.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person. In many cases this would be the name of the
guardian.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
admin-c: Joe T Bloggs
admin-c: JTB1
ripe-1nn.txt July, 1994
- 55 -
Status: mandatory, multiple lines allowed
guardian:
Mailbox of the guardian of the Autonomous system.
Format:
<email-address>
The <email-address> should be in RFC822 domain format
wherever possible.
Example:
guardian: as1104-guardian(a)nikhef.nl
Status: mandatory, only one line and e-mail address allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: Multihomed AS talking to AS1755 and AS786
remarks: Will soon connect to AS1104 also.
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be sent. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
ripe-1nn.txt July, 1994
- 56 -
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 57 -
Appendix B - Syntax details for the community object.
Here is a summary of the tags associated with community object
itself and their status. The first column specifies the attribute,
the second column whether this attribute is mandatory in the commun-
ity object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
community: [mandatory] [single]
descr: [mandatory] [multiple]
authority: [mandatory] [single]
guardian: [mandatory] [single]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
community:
Name of the community. The name of the community should be
descriptive of the community it describes.
Format:
Upper case text string which cannot start with "AS" or any
of the <routing policy expression> KEYWORDS. See Appendix
A.
Example:
community: WCW
Status: mandatory, only one line allowed
descr:
A short description of the community represented.
Format:
free text
Example:
descr: Science Park Watergraafsmeer
descr: Amsterdam
Status: mandatory, multiple lines allowed
ripe-1nn.txt July, 1994
- 58 -
authority:
The formal authority for this community. This could be an
organisation, institute, committee, etc.
Format:
free text
Example:
authority: WCW LAN Committee
Status: mandatory, only one line allowed
guardian:
Mailbox of the guardian of the community.
Format:
<email-address>
The <email-address> should be in RFC822 domain format
wherever possible.
Example:
guardian: wcw-guardian(a)nikhef.nl
Status: mandatory, only one line and email address allowed
tech-c:
Full name or uniquely assigned NIC-handle of an technical con-
tact person for this community.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person. In many cases this would be the name of the
guardian.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
admin-c: Joe T Bloggs
admin-c: JTB1
ripe-1nn.txt July, 1994
- 59 -
Status: mandatory, multiple lines allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: Temporary community
remarks: Will be removed after split into ASes
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
ripe-1nn.txt July, 1994
- 60 -
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 61 -
Appendix C - AS Macros syntax definition.
Here is a summary of the tags associated with as-macro object itself
and their status. The first column specifies the attribute, the
second column whether this attribute is mandatory in the as-macro
object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
as-macro: [mandatory] [single]
descr: [mandatory] [multiple]
as-list: [mandatory] [multiple]
guardian: [mandatory] [single]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
as-macro:
The name of a macro containing at least two Autonomous Systems
grouped together for ease of administration.
Format:
AS-<string>
The <string> should be in upper case and not contain any
special characters.
Example:
as-macro: AS-EBONE
Status: mandatory, only one line allowed
descr:
A short description of the Autonomous System Macro.
Format:
free text
Example:
descr: Macro for EBONE connected ASes
Status: mandatory, multiple lines allowed
ripe-1nn.txt July, 1994
- 62 -
as-list:
The list of ASes that make up this macro.
Format:
<aut-num> <aut-num> ...
See Appendix A for <aut-num> definition.
Example:
as-list: AS786 AS513 AS1104
Status: mandatory, multiple lines allowed
guardian:
Mailbox of the guardian of this AS macro.
Format:
<email-address>
The <email-address> should be in RFC822 domain format
wherever possible.
Example:
guardian: as-ebone-guardian(a)ebone.net
Status: mandatory, only one line and e-mail address allowed
tech-c:
Full name or uniquely assigned NIC-handle of a technical con-
tact person for this macro. This is someone to be contacted for
technical problems such as misconfiguration.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Examples:
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person. In many cases this would be the name of the
guardian.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Examples:
ripe-1nn.txt July, 1994
- 63 -
admin-c: Joe T Bloggs
admin-c: JTB1
Status: mandatory, multiple lines allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: AS321 will be removed from this Macro shortly
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
ripe-1nn.txt July, 1994
- 64 -
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 65 -
Appendix D - Syntax for the "route" object.
There is a summary of the tags associated with community object
itself and their status. The first column specifies the attribute,
the second column whether this attribute is mandatory in the commun-
ity object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
route: [mandatory] [single]
descr: [mandatory] [multiple]
origin: [mandatory] [single]
hole: [optional] [multiple]
withdrawn: [optional] [multiple]
comm-list: [optional] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
route:
Route being announced.
Format:
Classless representation of a route with the RIPE database
known as the "prefix length" representation. See [10] for
more details on classless representations.
Examples:
route: 192.87.45.0/24
This represents addressable bits 192.87.45.0 to
192.87.45.255.
route: 192.1.128.0/17
This represents addressable bits 192.1.128.0 to
192.1.255.255.
Status: mandatory, only one line allowed
origin:
The autonomous system announcing this route.
Format:
<aut-num>
ripe-1nn.txt July, 1994
- 66 -
See appendix A for <aut-num> syntax.
Example:
origin: AS1104
Status: mandatory, only one line allowed
hole:
Denote the parts of the address space covered this route object
to which the originator does not provide connectivity.
Format:
Classless representation of a route with the RIPE database
known as the "prefix length" representation. See [10] for
more details on classless representations. It should be
noted that is sub-aggregate must be a component of that
registered in the route object.
Example:
hole: 193.0.4.0/24
Status: optional, multiple lines allowed
withdrawn:
Used to denote the day this route has been withdrawn from the
Internet routing mesh. It should be noted that this date cannot
be in the future.
Format:
YYMMDD
YYMMDD denotes the date this route was withdrawn.
Example:
withdrawn: 940711
Status: optional, multiple lines allowed
comm-list:
List of one or more communities this route is part of.
Format:
<community> <community> ...
See Appendix B for <community> definition.
Example:
comm-list: HEP LEP
Status: optional, multiple lines allowed
ripe-1nn.txt July, 1994
- 67 -
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: Multihomed AS talking to AS1755 and AS786
remarks: Will soon connect to AS1104 also.
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
ripe-1nn.txt July, 1994
- 68 -
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 69 -
Appendix E - List of reserved words
The following list of words are reserved for use within the attri-
butes of the AS object. The use of these words is solely for the
purpose of clarity. All keywords must be lower case.
accept
announce
exclude
from
to
transit
Examples of the usage of the reserved words are:
as-in: from neighborAS accept route
as-out: to neighborAS announce route
as-exclude: exclude ASpath to destination
as-transit: transit ASpath to destination
default: from neighborAS accept route
default: to neighborAS announce route
Note: that as-transit is an experimental attribute. See section 10.
ripe-1nn.txt July, 1994
- 70 -
Appendix F - Motivations for RIPE-81++
This appendix gives motivations for the major changes in this propo-
sal from ripe-81. (It is not complete yet).
The main goals of the routing registry rework are:
SPLIT
Separate the allocation and routing registry functions into
different database objects. This will facilitate data manage-
ment if the Internet registry and routing registry functions
are separated (like in other parts of the world). It will also
make more clear what is part of the routing registry and who
has authority to change allocation vs. routing data.
CIDR
Add the possibility to specify classless routes in the routing
registry. Classless routes are being used in Internet produc-
tion now. Aggregation information in the routing registry is
necessary for network layer troubleshooting. It is also neces-
sary because aggregation influences routing policies directly.
CALLOC
Add the possibility to allocate address space on classless
boundaries in the allocation registry. This is a way to
preserve address space.
CLEAN
To clean up some of the obsolete and unused parts of the rout-
ing registry.
The major changes are now discussed in turn:
Introduce Classless Addresses
CIDR, CALLOC
Introduce route object.
SPLIT, CIDR and CALLOC.
Delete obsolete attributes from inetnum.
CLEAN.
ripe-1nn.txt July, 1994
- 71 -
Delete RIPE-DB and LOCAL from routing policy expressions.
CLEAN
Allow multiple ASes to originate the same route
Because it is being done. CIDR. Made possible by SPLIT.
ripe-1nn.txt July, 1994
- 72 -
Appendix G - Transition strategy from RIPE-81 to RIPE-81++
Transition from the routing registry described by ripe-81 to the
routing registry described in this document is a straightforward
process once the new registry functions have been implemented in the
database software and are understood by the most commonly used
registry tools. The routing related attributes in the classful inet-
num objects of ripe-81 can be directly translated into new routing
objects. Then these attributes can be deleted from the inetnum
object making that object conform to the new schema.
Proposed transition steps:
1) Implement classless addresses and new object definition in the
database software.
2) Make common tools understand the new schema and prefer it if
both old and new are present.
3) Invite everyone to convert their data to the new format. This
can be encouraged by doing conversions automatically and pro-
posing them to maintainers.
4) At a flag day remove all remaining routing information from the
inetnum objects. Before the flag day all usage of obsoleted
inetnum attributes has to cease and all other routing registry
functions have to be taken over by the new objects and attri-
butes.
The current estimate is that point three can be reached in the Sum-
mer 1994 if the draft is accepted by mid-June. The flag day should
be scheduled 3-4 months after this point.
ripe-1nn.txt July, 1994
6
9
>
> bonito(a)nis.garr.it (Antonio_Blasco Bonito) writes:
> * >
> Firstly,
> this is just my opinion.. it is up to the working group chairs
> to decide any new extensions here. I am just `trying' to complete the
> action for ripe-81++ from the last meeting. The points you raise are
> more general (esp. the time related one). However, find below my
> personal view on this.
>
> * > Ok, here are my last comments again (seens that last time they
> * > went directly to /dev/null). I won't accept a document which does not
> * > allow more than 1 update of an object per day.
> * > Laurent
> * >
> * > A few things i'd like to propose:
> * >
> * > - A route/AS name attribute. You currently use the first line of the 'des
> * c'
> * > attribute to generate a name (with prtraceroute for instance). Having
> * > a separate name attribute can make the query of the server (whois or what
> * ever)
> * > easier since it doesn't require any parsing.
> *
> * I strongly agree.
> *
> Umm... do not see the need for routes to have names - doesn't effect
> prtraceroute or any other tool for that matter. Whats to parse in
> description ? It is there in the aut-num object so a tool uses it..and
> works as far as I can tell ?
>
> However, if the groups want this fine by me. Just I didn't hear any
> other votes for this until now.
I'd vote for routes having names. I think the arguments for this are
essentially the same as in the discussion a couple of years ago about
whether nets needed names (or, more precisely, whether net names needed
to be unique). When working on routing problems, Routes will be the
entities that are looked at during the analysis like nets have been in
the past. Giving the tools the ability to put up even a slightly
descriptive name provides a lot of sanity checking. It also gives
a pronouncable verbal shorthand for human communication ("Hey, has that
JvNC AGG-one come back up yet?")
--Dale
1
0
Please find below a draft of a proposal for a router object known as
``inet-rtr''. This is the missing link of the current ripe-81++
specifically for the ias-int information which was rightly removed
along with the component attribute iself. This proposal is really a
modification of a similar proposal made by Merit with just one or two
clarifications and all credit belongs to them.
This object could very quickly added to the Database.
Please let me have comments asap.
--Tony.
Please note: a postscript version is available as
ftp://ftp.ripe.net/ripe/drafts/inet-rtr.ps
Specifying an `Internet Router' in the Routing
Registry
Tony Bates
DRAFT - DRAFT - DRAFT
Document ID: ripe-xy
ABSTRACT
This paper describes a simple specification for
defining an Internet router within a routing registry.
1. Introduction
It has become apparent as routing registries are evolving that there
is a need to register some details of an Internet router (1) within
the routing registry. By adding this kind of detailed information it
adds functionality to information based on routing policies [1]
facilitating the ability to build operational tools [2],[3] such as
configuration generators and diagnostic tools within increased local
information. It also provides a direct method to find a contact for
an important component of the Internet infrastructure. This can be
extremely useful when resolving operational problems.
2. Acknowledgments
This specification is based on a similar specification by Merit Inc.
for a `route' object (2). All credit should go to them. This paper
acts purely to clarify the original ideas set out in the Merit
paper.
_________________________
(1) Here an Internet router means any IP [4] node ca-
pable of running an IP routing protocol. Be that RIP,
BGP or any other of the current IP based routing proto-
cols found in the Internet today. This definition is
intentionally looser than what might be found in the
"Router requirements" Internet draft [5].
(2) This specification does not use `router' as the
object name to avoid possible clashes with the `route'
object which already exists within the routing regis-
try.
ripe-xy.txt July, 1994
- 2 -
3. Router Representation
The representation must be capable of representing both ``interior''
and ``border'' routers within ones own autonomous system. Each
object is uniquely identified by its object name. Here is a simple
example of a router object:
inet-rtr: Amsterdam.ripe.net
localas: AS3333
ifaddr: 192.87.45.190
ifaddr: 192.87.4.28
ifaddr: 193.0.0.222
peer: 192.87.45.6 AS2122 BGP4
peer: 193.0.0.219 AS2122 BGP
peer: 193.0.0.221 AS1104 BGP
peer: 192.87.4.18 AS1103 BGP4
peer: 192.87.4.24 AS1103 BGP4
peer: 192.87.4.20 AS286 BGP4
peer: 192.87.4.5 AS3333 IBGP4
admin-c: Daniel Karrenberg
tech-c: Tony Bates
tech-c: Marten Terpstra
notify: ops(a)ripe.net
remarks: The router for the RIPE NCC
changed: tony(a)ripe.net 940720
source: RIPE
This object provides several key pieces of information. The exact
syntax for each attribute is discussed in the next section. However,
some general remarks about this example are worthy of note. From
this you can see immediately that this router "Amsterdam.ripe.net"
is in the autonomous system 3333 and has three configured inter-
faces. You also see that it has several exterior peers and one inte-
rior peer (192.87.45.6). Details of the actual routing protocol are
given. This can be extremely useful. For example a BGP3 router is
not CIDR [6] capable whereas a BGP4 capable router is. A tool could
use this information when examining routing policy to see if a peer
can make use of aggregation. Finally, we also see who we can con-
tact when problems occur with this router.
ripe-xy.txt July, 1994
- 3 -
4. `inet-rtr' Syntax Definition
Here is a summary of the tags associated with inet-rtr object itself
and their status. The first column specifies the attribute, the
second column whether this attribute is mandatory in the inet-rtr
object, and the third column whether this specific attribute can
occur only once per object [single], or one or more [multiple]. When
specifying multiple lines per attribute, the attribute name must be
repeated.
inet-rtr: [mandatory] [single]
localas: [mandatory] [single]
ifaddr: [mandatory] [multiple]
peer: [optional] [multiple]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
inet-rtr:
The fully qualified domain name of the router.
Format:
Fully qualified domain name without trailing "." (dot).
This must be registered in the DNS. For routers with more
than one DNS you should pick the one that seems most suit-
able. It should be noted that it is commonly general prac-
tice for a router to have single uniquely defined domain
name.
Example:
inet-rtr: Amsterdam.ripe.net
Status: mandatory, only one line allowed
localas:
The autonomous system in which this router belongs.
Format:
AS<positive integer between 1 and 65535>
Example:
localas: AS3333
Status: mandatory, only one line allowed
ripe-xy.txt July, 1994
- 4 -
ifaddr:
An interface address within the router.
Format:
<Interface Address> [Local AS]
<Interface Address> must be a "dotted-quad" represented
host address. It should be noted that at ONE ifaddr must
be configured for the inet-rtr object to be valid. This
facilitates the registering of route servers which may
only have one interface address and are purely routing
engines.
[Local AS] is an optional piece of information which
allows this interface to be configured as being in a DIF-
FERENT autonomous system. This is useful only when a
router is configured to `fake' that it is another AS. The
format of [Local AS] is AS<positive integer between 1 and
65535>.
Examples:
ifaddr: 192.87.45.190
ifaddr: 192.87.4.99 AS1755
Status: mandatory, multiple lines allowed
peer:
Details of any router peerings. These can be both interior or
exterior.
Format:
<Peer address> <Peer AS> <Routing Protocol>
<Peer address> is the interface address of the remote
peer. This is same format as that used in the ``ifaddr''
attribute above.
<Peer AS> is the autonomous system number of the peer. Its
format is AS<positive integer between 1 and 65535>. It
should be noted that even interior peers should have their
<Peer AS> detailed.
<Routing Protocol> represents the routing protocol running
between the router and the peer. This can be any one of
the following reserved routing protocol keywords:
EGP
The routers are using the exterior gateway protocol,
EGP [7].
BGP
The routers are using the exterior gateway protocol,
BGP conforming to [8]. This can mean either BGP
ripe-xy.txt July, 1994
- 5 -
version 2 or BGP version 3.
BGP4
The routers are using the exterior gateway protocol,
BGP conforming to BGP version 4 [9].
IBGP
The routers are using the exterior gateway protocol,
BGP as an interior routing protocol conforming to
[8]. This can mean either BGP version 2 or BGP ver-
sion 3.
IBGP4
The routers are using the exterior gateway protocol,
BGP as an interior routing protocol conforming to BGP
version 4 [9].
IDRP
The routers are using the exterior gateway protocol,
IDRP conforming to [10].
IGP
This is an interior peering using a standard interior
gateway protocol (i.e. RIP, OSPF, etc.).
OTHER
This peering is using a protocol not in one of the
categories above.
Example:
peer: 192.87.45.6 AS2122 BGP4
peer: 193.0.0.219 AS2122 BGP
peer: 193.0.0.221 AS1104 BGP
peer: 192.87.4.18 AS1103 BGP4
peer: 192.87.4.24 AS1103 BGP4
peer: 192.87.4.20 AS286 BGP4
peer: 192.87.4.5 AS3333 IBGP4
Status: optional, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Examples:
admin-c: Joe T Bloggs
admin-c: JTB1
Status: mandatory, multiple lines allowed
ripe-xy.txt July, 1994
- 6 -
tech-c:
Full name or uniquely assigned NIC-handle of a technical con-
tact person for this macro. This is someone to be contacted for
technical problems such as misconfiguration.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Examples:
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send.
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: This is a router
ripe-xy.txt July, 1994
- 7 -
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-xy.txt July, 1994
- 8 -
5. References
[1] Bates, T., Gerich, E., Joncheray, L., Joanigot, J-M, Karren-
berg, D., Terpstra, M, Yu, J., ripe-81++, July 1994. WORK IN
PROGRESS
[2] PRIDE Tools Release 1.
See ftp.ripe.net:pride/tools/pride-tools-1.tar.Z.
[3] Merit Inc. RRDB Tools.
See rrdb.merit.edu:pub/meritrr/*
[4] J. Postel, "Internet Protocol", RFC 791, January 1981.
[5] Kastenholz, F., draft-ietf-rreq-iprouters-require-01.txt,
April, 1994, INTERNET DRAFT
[6] V. Fuller, T. Li, J. Yu, K. Varadhan, "Classless Inter-Domain
Routing (CIDR): an Address Assignment and Aggregation Stra-
tegy", RFC1519, Sep., 1993.
[7] Mills, D., "Exterior Gateway Protocol formal specification",
RFC904, April 1984.
[8] K. Lougheed, Y. Rekhter, "A Border Gateway Protocol 3 (BGP-3)",
RFC1267, October 1991.
[9] Y. Rekhter, T. Li, "A Border Gateway Protocol 4 (BGP-4)",
<draft-ietf-bgp-bgp4-10.txt>, INTERNET DRAFT, May, 1994.
[10] C. Kunzinger, "ISO/IEC 10747 - Protocol for the Exchange of
Inter-Domain Routing Information among Intermediate Systems to
Support Forwarding of ISO 8473 PDUs", <draft-kunzinger-idrp-
ISO10747-00.txt>, INTERNET DRAFT, April 1994.
ripe-xy.txt July, 1994
2
7
Please find below the latest draft of ripe-81++. This has several
changes which have been worked in, over the weeks following the RIPE
meeting as agreed. There are still a couple of open issues for which
we are waiting on input. However, these have been clearly separated
(and marked) such that we can (and will) begin implementing the rest
of ripe-81++.
We would like to have this agreed by the next RIPE meeting at the very
latest (if not sooner) to make sure implementation work can take
place. If this is not done it may be next year before implementation
work can begin on this.
--Tony.
Also note that both this and the postscript version are available from
ftp://ftp.ripe.net/ripe/drafts/ripe-81++.ps
ftp://ftp.ripe.net/ripe/drafts/ripe-81++.txt
Representation of IP Routing Policies
in a Routing Registry
(ripe-81++)
DRAFT DRAFT DRAFT
Tony Bates
Elise Gerich
Laurent Joncheray
Jean-Michel Jouanigot
Daniel Karrenberg
Marten Terpstra
Jessica Yu
Document-ID: ripe-1nn
Obsoletes: ripe-81
July, 1994
ABSTRACT
This document is an update to the original `ripe-
81'[1] proposal for representing and storing routing
polices within the RIPE database. It incorporates
several extensions proposed by Merit Inc.[2] and gives
details of a generalised IP routing policy representa-
tion to be used by all Internet routing registries. It
acts as both tutorial and provides details of database
objects and attributes that use and make up a routing
registry.
ripe-1nn.txt July, 1994
- 2 -
Table of Contents
1 Introduction ................................................ ?
2 Organisation of this Document ............................... ?
3 General Representation of Policy Information ................ ?
4 The Routing Registry and the RIPE Database .................. ?
5 The Route Object ............................................ ?
6 The Autonomous System Object ................................ ?
7 The AS Macro Object ......................................... ?
8 The Community Object ........................................ ?
9 Representation of Routing Policies .......................... ?
10 Future Extensions .......................................... ?
11 References ................................................. ?
12 Authors Addresses .......................................... ?
Appendix A - Syntax for the "aut-num" object .................. ?
Appendix B - Syntax for the "community" object ................ ?
Appendix C - Syntax for the "as-macro" object ................. ?
Appendix D - Syntax for the "route" object .................... ?
Appendix E - List of reserved words ........................... ?
Appendix F - Motivations for RIPE-81++ ........................ ?
Appendix G - Transition strategy from RIPE-81 to RIPE-81++ .... ?
ripe-1nn.txt July, 1994
- 3 -
1. Introduction
This document is a much revised version of the RIPE routing registry
document known as ripe-81[1]. Since its inception in February, 1993
and the establishment of the RIPE routing registry, several addi-
tions and clarifications have come to light which can be better
presented in a single updated document rather than separate addenda.
Some of the text remains the same the as the original ripe-81 docu-
ment keeping its tutorial style mixed with details of the RIPE data-
base objects relating to routing policy representation. However
this document does not repeat the background and historical remarks
in ripe-81. For these please refer to the original document. It
should be noted that whilst this document specifically references
the RIPE database and the RIPE routing registry one can easily read
"Regional routing registry" in place of RIPE as this representation
is certainly general and flexible enough to be used outside of the
RIPE community incorporating many ideas and features from other
routing registries in this update.
As you can see this document has a new RIPE document identification
number but can also be referred to as ripe-81++. Appendix F summar-
ises the changes from ripe-81 plus the motivation for these changes.
We would like to acknowledge many people for help with this docu-
ment. Specifically, Peter Lothberg who was a co-author of the ori-
ginal ripe-81 document for his many ideas and Gilles Farrache. We
would also like to thank the RIPE routing working group for their
review and comment. Finally, we like to thank Merit Inc. for many
constructive comments and ideas and making the routing registry a
worldwide Internet service. We would also like to acknowledge the
funding provided by the PRIDE project run in conjunction with the
RARE Technical Program, RIPE and the RIPE NCC without which this
paper would not have been possible.
2. Organisation of this Paper
This paper acts as both a basic tutorial for understanding routing
policy and provides details of objects and attributes used within an
Internet routing registry to store routing policies. Section 3
describes general issues about IP routing policies and their
representation in routing registries. Experienced readers may wish
to skip this section. Section 4 provides an overview of the RIPE
database, its basic concepts, schema and objects which make up the
database itself. It highlights the way in which the RIPE database
splits routing information from allocation information. Sections 5,
6, 7 and 8 detail all the objects associated with routing policy
representation. Section 9 gives a fairly extensive "walk through"
of how these objects are used for expressing routing policy and the
general principles behind their use. Section 10 provides a list of
references used throughout this document. Appendix A, B, C and D
document the formal syntax for the database objects and attributes.
Appendix F details the main changes from ripe-81 and motivations for
these changes. Appendix G tackles the issues of transition from
ripe-1nn.txt July, 1994
- 4 -
ripe-81 to ripe-81++.
ripe-1nn.txt July, 1994
- 5 -
3. General Representation of Policy Information
Networks, Network Operators and Autonomous Systems
Throughout this document an effort is made to be consistent with
terms so as not to confuse the reader.
When we talk about "networks" we mean physical networks which have a
unique classless IP network number: Layer 3 entities. We do not mean
organisations.
We call the organisations operating networks "network operators".
For the sake of the examples we divide network operators into two
categories: "service providers" and "customers". A "service pro-
vider" is a network operator who operates a network to provide
Internet services to different organisations, its "customers". The
distinction between service providers and customers is not clear
cut. A national research networking organisation frequently acts as
a service provider to Universities and other academic organisations,
but in most cases it buys international connectivity from another
service provider. A University networking department is a customer
of the research networking organisation but in turn may regard
University departments as its customers.
An Autonomous System (AS) is a group of IP networks having a single
clearly defined routing policy which is run by one or more network
operators. Inside ASes IP packets are routed using one or more Inte-
rior Routing Protocols (IGPs). In most cases interior routing deci-
sions are based on metrics derived from technical parameters like
topology, link speeds and load(1).
ASes exchange routing information with other ASes using Exterior
Routing Protocols (EGPs). Exterior routing decisions are frequently
based on policy based rules rather than purely on technical parame-
ters. Tools are needed to configure complex policies and to commun-
icate those policies between ASes while still ensuring proper opera-
tion of the Internet as a whole. Some EGPs like BGP-3 [8] and BGP-4
[9] provide tools to filter routing information according to policy
rules and more. None of them provides a mechanism to publish or com-
municate the policies themselves. Yet this is critical for opera-
tional coordination and fault isolation among network operators and
thus for the operation of the global Internet as a whole. This
document describes a "Routing Registry" providing this functional-
ity.
_________________________
(1) The entity we refer to as an AS is frequently and
more generally called a routing domain with the AS just
being an implementation vehicle. We have decided to use
the term AS exclusively because it relates more direct-
ly with the database objects and routing tools. By us-
ing only one term we hope to reduce the number of con-
cepts and to avoid confusion. The academically inclined
reader may forgive us.
ripe-1nn.txt July, 1994
- 6 -
Routing Policies
The exchange of routing information between ASes is subject to rout-
ing policies. Consider the case of two ASes, X and Y exchanging
routing information:
NET1 ...... ASX <---> ASY ....... NET2
ASX knows how to reach a network called NET1. It does not matter
whether NET1 is belonging to ASX or some other AS which exchanges
routing information with ASX either directly or indirectly; we just
assume that ASX knows how to direct packets towards NET1. Likewise
ASY knows how to reach NET2.
In order for traffic from NET2 to NET1 to flow between ASX and ASY,
ASX has to announce NET1 to ASY using an external routing protocol.
This states that ASX is willing to accept traffic directed to NET1
from ASY. Policy thus comes into play first in the decision of ASX
to announce NET1 to ASY.
In addition ASY has to accept this routing information and use it.
It is ASY's privilege to either use or disregard the information
that ASX is willing to accept traffic for NET1. ASY might decide not
to use this information if it does not want to send traffic to NET1
at all or if it considers another route more appropriate to reach
NET1.
So in order for traffic in the direction of NET1 to flow between ASX
and ASY, ASX must announce it to ASY and ASY must accept it from
ASX:
resulting packet flow towards NET1
<<===================================
|
|
announce NET1 | accept NET1
--------------> + ------------->
|
AS X | AS Y
|
<------------- + <--------------
accept NET2 | announce NET2
|
|
resulting packet flow towards NET2
===================================>>
Ideally, and seldom practically, the announcement and acceptance
policies of ASX and ASY are identical.
ripe-1nn.txt July, 1994
- 7 -
In order for traffic towards NET2 to flow, announcement and accep-
tance of NET2 must be in place the other way round. For almost all
applications connectivity in just one direction is not useful at
all.
It is important to realise that with current destination based for-
warding technology routing policies must eventually be expressed in
these terms. It is relatively easy to formulate reasonable policies
in very general terms which CANNOT be expressed in terms of announc-
ing and accepting networks. With current technology such policies
are almost always impossible to implement.
Usually policies are not configured for each network separately but
for groups of networks. In practise these groups are almost always
defined by the networks forming one or more ASes.
Routing Policy limitations
The generic example of a reasonable but un-implementable routing is
a split of already joined packet streams based on something other
than destination address. Once traffic for the same destination
network passes the same router, or the same AS at our level of
abstraction, it will take exactly the same route to the destina-
tion(2).
In a concrete example AS Z might be connected to the outside world
by two links. AS Z wishes to reserve these links for different
kinds of traffic, let's call them black and white traffic. For this
purpose the management of AS Z keeps two lists of ASes, the black
and the white list. Together these lists comprise all ASes in the
world reachable from AS Z.
"W"
<--->
... AS Z .... NET 3
<--->
"B"
It is quite possible to implement the policy for traffic originating
in AS Z: AS Z will only accept announcements for networks in white
ASes on the white link and will only accept announcements for net-
works in black ASes on the black link. This causes traffic from
networks within AS Z towards white ASes to use the white link and
likewise traffic for black ASes to use the black link.
Note that this way of implementing things makes it necessary to
decide on the colour of each new AS which appears before traffic can
be sent to it from AS Z. A way around this would be to accept only
_________________________
(2) Disregarding special cases like "type of service"
routing, load sharing and routing instabilities.
ripe-1nn.txt July, 1994
- 8 -
white announcements via the white link and to accept all but white
announcements on the black link. That way traffic from new ASes
would automatically be sent down the black link and AS Z management
would only need to keep the list of white ASes rather than two
lists.
Now for the unimplementable part of the policy. This concerns
traffic towards AS Z. Consider the following topology:
B AS ---) "W"
W AS ---) --->
B AS ---)>> AS A ---> ... AS Z .... NET 3
B AS ---) --->
W AS ---) "B"
As seen from AS Z there are both black and white ASes "behind" AS A.
Since ASes can make routing decisions based on destination only, AS
A and all ASes between AS A and the two links connecting AS Z can
only make the same decision for traffic directed at a network in AS
Z, say NET 3. This means that traffic from both black and white
ASes towards NET 3 will follow the same route once it passes through
AS A. This will either be the black or the white route depending on
the routing policies of AS A and all ASes between it and AS Z.
The important thing to note is that unless routing and forwarding
decisions can be made based on both source and destination
addresses, policies like the "black and white" example cannot be
implemented in general because "once joined means joined forever".
Access Policies
Access policies contrary to routing policies are not necessarily
defined in terms of ASes. The very simplest type of access policy is
to block packets from a specific network S from being forwarded to
another network D. A common example is when some inappropriate use
of resources on network D has been made from network S and the prob-
lem has not been resolved yet. Other examples of access policies
might be resources only accessible to networks belonging to a par-
ticular disciplinary group or community of interest. While most of
these policies are better implemented at the host or application
level, network level access policies do exist and are a source of
connectivity problems which are sometimes hard to diagnose. There-
fore they should also be documented in the routing registry accord-
ing to similar requirements as outlined above.
Routing v Allocation information
The RIPE database contains both routing registry and address space
allocation registry information. In the past the database schema
combined this information. Because RIPE was tasked with running both
an allocation and routing registry it seemed natural to initially
ripe-1nn.txt July, 1994
- 9 -
combine these functions. However, experience has shown that a clear
separation of routing information from allocation is desirable.
Often the maintainer of the routing information is not the same as
the maintainer of the allocation information. Also, in other parts
of the world there are different registries for each kind of infor-
mation.
Whilst the actual routing policy objects will be introduced in the
next section it is worthy of note that a transition from the current
objects will be required. This is described with in Appendix G.
This split in information represents a significant change in the
representational model of the RIPE database. Appendix F expands on
the reasons for this a little more.
Tools
The network operators will need a series of tools for policy rout-
ing. Some tools are already available to perform some of the tasks.
Most notably, the PRIDE tools [3] from the PRIDE project started in
September 1993 as well as others produced by Merit Inc [4] and CERN
[5].
These tools will enable them to use the routing policy stored in the
RIPE routing registry to perform such tasks as check actual routing
against policies defined, ensure consistency of policies set by dif-
ferent operators, and simulate the effects of policy changes.
Work continues on producing more useful tools to service the Inter-
net community.
ripe-1nn.txt July, 1994
- 10 -
4. The Routing Registry and the RIPE Database
One of the activities of RIPE is to maintain a database of Euro-
pean IP networks, DNS domains and their contact persons along with
various other kinds of network management information. The database
content is public and can be queried using the whois protocol as
well as retrieved as a whole. This supports NICs/NOCs all over
Europe and beyond to perform their respective tasks.
The RIPE database combines both allocation registry and routing
registry functions. The RIPE allocation registry contains data
about address space allocated to specific enterprises and/or
delegated to local registries as well as data about the domain name
space. The allocation registry is described in separate documents
[6,7] and outside the scope of this document.
Database Objects
Each object in the database describes a single entity in the real
world. This basic principle means that information about that
entity should only be represented in the corresponding data-
base object and not be repeated in other objects. The whois ser-
vice can automatically display referenced objects where appropriate.
The types of objects stored in the RIPE database are summarised in
the table below:
R Object Describes References
____________________________________________________________________
B person contact persons
A inetnum IP address space person
A domain DNS domain person
R aut-num autonomous system person
(aut-num,community)
R as-macro a group of autonomous systems person, aut-num
R community community person
R route a route being announced aut-num, community
R clns CLNS address space and routing person
The first column indicates whether the object is part of the alloca-
tion registry (A), the routing registry (R) or both (B). The last
column indicates the types of objects referenced by the particular
type of object. It can be seen that almost all objects reference
contact persons.
Objects are described by attributes value pairs, one per line.
Objects are separated by empty lines. An attribute that consists
ripe-1nn.txt July, 1994
- 11 -
of multiple lines should have the attribute name repeated on
consecutive lines. The information stored about network 192.87.45.0
consists of three objects, one network object and two person
objects and looks like this:
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
person: Daniel Karrenberg
address: RIPE Network Coordination Centre (NCC)
address: Kruislaan 409
address: NL-1098 SJ Amsterdam
address: Netherlands
phone: +31 20 592 5065
fax-no: +31 20 592 5090
e-mail: dfk(a)ripe.net
nic-hdl: DK58
changed: ripe-dbm(a)ripe.net 920826
source: RIPE
person: Marten Terpstra
address: RIPE Network Coordination Centre (NCC)
address: PRIDE Project
address: Kruislaan 409
address: NL-1098 SJ Amsterdam
address: Netherlands
phone: +31 20 592 5064
fax-no: +31 20 592 5090
e-mail: Marten.Terpstra(a)ripe.net
nic-hdl: MT2
notify: marten(a)ripe.net
changed: marten(a)ripe.net 931230
source: RIPE
Objects are stored and retrieved in this tag/value format. The RIPE
NCC does not provide differently formatted reports because any
desired format can easily be produced from this generic one.
ripe-1nn.txt July, 1994
- 12 -
Routing Registry Objects
The main objects comprising the routing registry are "aut-num" and
"route", describing an autonomous system and a route respectively.
It should be noted that routes not described in the routing registry
should never be routed in the Internet itself.
The autonomous system (aut-num) object provides contact information
for the AS and describes the routing policy of that AS. The routing
policy is described by enumerating all neighbouring ASes with which
routing information is exchanged. For each neighbour the routing
policy is described in terms of exactly what is being sent
(announced) and allowed in (accepted). It is important to note that
this is exactly the part of the global policy over which an AS has
direct control. Thus each aut-num object describes what can indeed
be implemented and enforced locally by the AS concerned. Combined
together all the aut-num objects provide the global routing graph
and permit to deduce the exact routing policy between any two ASes.
While the aut-num objects describe how routing information is pro-
pagated, the route object describes a single route injected into the
external routing mesh. The route object references the AS injecting
(originating) the route and thereby indirectly provides contact
information for the originating AS. This reference also provides the
primary way of grouping routes into larger collections. This is
necessary because describing routing policy on the level of single
routes would be awkward to impractical given the number of routes in
the Internet which is about 20,000 at the time of this writing.
Thus routing policy is most often defined for groups of routes by
originating AS. This method of grouping is well supported by
current exterior routing protocols. The route object also refer-
ences community objects described below to provide another method of
grouping routes. Modification of aut-num object itself and the
referencing by route objects is strictly protected to provide net-
work operators control over the routing policy description and the
routes originated by their ASes.
Sometimes even keeping track of groups of routes at the AS level is
cumbersome. Consider the case of policies described at the transit
provider level which apply transitively to all customers of the
transit provider. Therefore another level of grouping is provided by
the as-macro object which provides groups of ASes which can be
referenced in routing policies just like single ASes. Membership of
as-macro groups is also strictly controlled.
Sometimes there is a need to group routes on different criteria than
ASes for purposes like statistics or local access policies. This is
provided by the community object. A community object is much like
an AS but without a routing policy. It just describes a group of
routes. This is not supported at all by exterior routing protocols
and depending on aggregation of routes may not be generally usable
to define routing policies. It is suitable for local policies and
non-routing related purposes.
ripe-1nn.txt July, 1994
- 13 -
These routing related objects will be described in detail in the
sections below.
ripe-1nn.txt July, 1994
- 14 -
5. The Route Object
As stated in the previous chapter routing and address space alloca-
tion information are now clearly separated. This is performed with
the introduction of the route object. The route object will contain
all the information regarding a routing announcement.
All routing related attributes are removed from the inetnum object.
Some old attributes are obsoleted: connect, routpr-l, bdryg-l, nsf-
in, nsf-out, gateway). The currently useful routing attributes are
moved to the route object: aut-sys becomes origin, ias-int will be
encoded as part of the "to be proposed" `border-router' object and
comm-list simply moves. See [6] for detail of the "inetnum" object
definition.
The information in the old inetnum object
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
connect: RIPE NSF WCW
aut-sys: AS3333
comm-list: SURFNET
ias-int: 192.87.45.80 AS1104
ias-int: 192.87.45.6 AS2122
ias-int: 192.87.45.254 AS2600
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
will be distributed over two objects:
ripe-1nn.txt July, 1994
- 15 -
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
route: 192.87.45.0/24
descr: RIPE Network Coordination Centre
origin: AS3333
comm-list: SURFNET
changed: dfk(a)ripe.net 940427
source: RIPE
The route object is used to represent a single route originated into
the Internet routing mesh. The actual syntax is given in Appendix
D. However, there are several important aspects of the attributes
worthy of note.
The value of the route attribute will be a classless address. It
represents the exact route being injected into the routing mesh.
The representation of classless addresses is described in [10].
The value of the origin attribute will be an AS reference of the
form AS1234 referring to an aut-num object. It represents the AS
injecting this route into the routing mesh. The "aut-num" object
(see below) thus referenced provides all the contact information for
this route.
Special cases: There can only be a single originating AS in each
route object. However in todays Internet sometimes a route is
injected by more than one AS. This situation is potentially
dangerous as it can create conflicting routing policies for that
route and requires coordination between the originating ASes. In
the routing registry this is represented by multiple route objects.
This is a departure from the one route (net), one AS principle of
the ripe-81 routing registry. The consequences for the different
tools based in the routing registry will need to be evaluated and
possibly additional consistency checking of the database is needed.
ripe-1nn.txt July, 1994
- 16 -
The examples below will illustrate the usage of the route object
further. Suppose three chunks of address space of 2 different
enterprises represented by the following inetnum objects:
Examples
inetnum: 193.0.1.0
netname: ENT-1
descr: Enterprise 1
...
inetnum: 193.0.8.0
netname: ENT-2
descr: Enterprise 2
...
inetnum: 193.0.9.0
netname: ENT-2-SPEC
descr: Enterprise 2
...
Supposing that the Enterprises have their own AS numbers straight
application of routing without aggregation would yield:
route: 193.0.1.0/24
descr: Enterprise 1
origin: AS1
...
route: 193.0.8.0/24
descr: Enterprise 2
origin: AS2
...
route: 193.0.9.0/24
descr: Enterprise 2
origin: AS2
...
NB: This representation can be achieved by straight translation from
the ripe-81 representation. See Appendix G for more details.
Homogeneous Aggregation
The two chunks of address space of Enterprise 2 can be represented
by one aggregate route turning two route objects into one and poten-
tially saving routing table space for one route.
ripe-1nn.txt July, 1994
- 17 -
route: 193.0.8.0/23
descr: Enterprise 2
origin: AS2
...
Note that AS2 can also decide to originate all routes mentioned so
far, two 24-bit prefixes and one 23-bit prefix. This case would be
represented by storing all three route objects in the database. In
this particular example the additional routes will not add any func-
tionality however and only increase the amount of routes announced
unnecessarily.
Heterogeneous Aggregation
Consider the following case however:
route: 193.0.8.0/24
descr: Enterprise 2
origin: AS2
...
route: 193.0.9.0/24
descr: Enterprise 2 / Special
origin: AS2
comm-list: SPECIAL
...
Now the prefix 193.0.9.0/24 belongs to community SPECIAL (this com-
munity may well not be relevant to routing) and the other prefix
originated by AS2 does not. If AS2 aggregates these prefixes into
the 193.0.8.0/23 prefix, routing policies based on the community
value SPECIAL cannot be implemented in general, because there is no
way to distinguish between the special and the not-so-special parts
of AS2. If another AS has the policy to accept only routes to
members of community SPECIAL it cannot implement it, because accept-
ing the route to 193.0.8.0/23 would also route to 193.0.8.0/24 and
not accepting this route would lose connectivity to the special part
193.0.9.0/24. We call aggregate routes consisting of components
belonging to different communities or even different ASes "hetero-
geneous aggregates".
The problems introduced with heterogeneous aggregates are that once
the homogeneous routes are withdrawn one cannot tell if a more
specific part of the heterogeneous has a different policy. However,
if can be counter argued that knowing this policy is of little use
if you cannot implement a routing policy based on the less specific
(and only route present) heterogeneous aggregate. In fact, this
displays a facet of CIDR itself in that one may actually compromise
slight variations on policy over announcing a larger (albeit
ripe-1nn.txt July, 1994
- 18 -
heterogeneous in terms of policy) aggregate to save address space.
However, it is still useful to be able to document these variations
in policy especially when this homogeneous more specific route is
just being withdrawn. For this one can use the "withdrawn" attri-
bute. The withdrawn attribute can serve to both indicate that a less
specific aggregate is in fact heterogeneous and also allow the gen-
eral documenting of route withdrawal.
So there has to be a way for AS2 to document this even if it does
not originate the route to 193.0.9.0/24 any more. This can be done
with the "withdrawn" attribute of the route object. The aggregate
route to 193.0.8.0/23 is now be registered as:
route: 193.0.8.0/23
descr: Enterprise 2
origin: AS2
...
With the two homogeneous routes marked as withdrawn from the Inter-
net routing mesh but still preserving their original routing infor-
mation.
route: 193.0.8.0/24
descr: Enterprise 2
origin: AS2
withdrawn: 940701
...
route: 193.0.9.0/24
descr: Enterprise 2 / Special
origin: AS2
comm-list: SPECIAL
withdrawn: 940701
...
It should be noted that the date value used in the withdrawn attri-
bute can only be in the past.
Proxy Aggregation
The next step of aggregation are aggregates consisting of more than
one AS. This generally means one AS is aggregating on behalf of
another. It is called proxy aggregation. Proxy aggregation should be
done with great care and always coordinates with other providers
announcing the same route.
Consider the following:
ripe-1nn.txt July, 1994
- 19 -
route: 193.0.0.0/20
descr: All routes known by AS1 in a single package
origin: AS1
...
route: 193.0.1.0/24
descr: Foo
origin: AS1
withdrawn: 940310
...
route: 193.0.8.0/24
descr: Bar
origin: AS2
withdrawn: 940310
...
route: 193.0.9.0/24
descr: Bar-2
origin: AS2
withdrawn: 940310
comm-list: SPECIAL
...
If AS1 announced no other routes to a single homed neighbouring AS,
that neighbour can in general either take that route or leave it but
not differentiate between AS1 and AS2.
Note: If the neighbor was previously configured to accept routes
originating in AS2 but not in AS1 they lose connectivity to AS2 as
well. This means that proxy aggregation has to be done carefully
and in a well coordinated fashion. The information in the withdrawn
route object can help to achieve that.
Aggregates with Holes
If we assume that the world of our example still consists of only
three chunks of address space the aggregate above contains what are
called holes, parts of an aggregate that are not reachable via the
originator of the route. From the routing information itself one
cannot tell whether these are holes and what part of the route falls
inside one. The only way to tell is to send a packet there and see
ripe-1nn.txt July, 1994
- 20 -
whether it gets to the destination, or an ICMP message is received
back, or there is silence. On the other hand announcing aggregates
with holes is quite legitimate. Consider a 16-bit aggregate with
only one 24-bit prefix unreachable. The savings in routing table
size by far outweigh the hole problem.
For operational reasons however it is very useful to register these
holes in the routing registry. Consider the case where a remote net-
work operator experiences connectivity problems to addresses inside
an aggregate route. If the packets are getting to the AS announcing
the aggregate and there are no more specific routes, the normal
cause of action is to get in touch with the originating AS of the
aggregate route and ask them to fix the problem. If the address
falls into a hole this is futile. Therefore problem diagnosis can be
sped up and unnecessary calls prevented by registering the holes in
the routing registry. We do this by using the "hole" attribute. In
our example the representation would be:
route: 193.0.0.0/20
descr: All routes known by AS1
origin: AS1
hole: 193.0.0.0/24
hole: 193.0.2.0/23
hole: 193.0.4.0/22
hole: 193.0.10.0/23
hole: 193.0.12.0/22
...
Note: there would also be two routes with the withdrawn attribute as
displayed above (i.e. 193.0.8.0/24 and 193.0.9.0/24)
Multiple Proxy Aggregation
Finally suppose that AS2 decides to announce the same aggregate,
they would add the following route object to the registry:
route: 193.0.0.0/20
descr: All routes known by AS2
origin: AS2
hole: 193.0.0.0/24
hole: 193.0.2.0/23
hole: 193.0.4.0/22
hole: 193.0.10.0/23
hole: 193.0.12.0/22
...
As per the update procedures below both AS1 and AS2 will be notified
that there already is a route to the same prefix in the registry.
This multiple proxy aggregation is very dangerous to do if the sub-
ripe-1nn.txt July, 1994
- 21 -
aggregates of the route are not the same. It is still dangerous when
the sub-aggregates are consistent but connectivity to the sub-
aggregates varies widely between the originators.
Route object update procedures
Adding a route object will be have to be authorised by the guardian
of the originating AS. The actual implementation of this is outside
the scope of this document. This guarantees that an AS guardian has
full control over the registration of the routes it announces.
What is an Inter-AS network ?
An inter-AS network(3) exists for the purpose of passing traffic and
routing information between different autonomous systems. The most
simple example of an inter-AS network is a point-to-point link, con-
necting exactly two ASes. Each end of such a link is connected to
an interface of router belonging to each of the autonomous systems.
More complex examples are broadcast type networks with multiple
interfaces connecting multiple ASes with the possibility of more
than one connection per AS. Consider the following example of three
routers 1, 2 and 3 with interfaces a through f connected by two
inter-AS networks X and Y:
X Y
a1b --- c2d --- e3f
Suppose that network X is registered in the routing registry as part
of AS1 and net Y as part of AS3. If traffic passes from left to
right prtraceroute will report the following sequence of interfaces
and ASes:
a in AS1
c in AS1
e in AS3
The traceroute algorithm enumerates only the receiving interfaces on
the way to the destination. In the example this leads to the pas-
sage of AS2 going unnoticed. This is confusing to the user and will
also generate exceptions when the path found is checked against the
routing registry.
_________________________
(3) Inter-AS IP networks are those networks are
currently called FIXes, IXFs, DMZs, NAPs, GIX and many
other acronyms.
ripe-1nn.txt July, 1994
- 22 -
For operational monitoring tools such as prtraceroute it is neces-
sary to know which interface on an inter-AS network belongs to which
AS. If AS information is not known about interfaces on an inter-AS
network, tools like prtraceroute cannot determine correctly which
ASes are being traversed.
All interfaces on inter-AS networks will be described in a separate
object know as the `border-router' object. This is still to be
defined.
ripe-1nn.txt July, 1994
- 23 -
6. The Autonomous System Object
Autonomous Systems
An Autonomous System (AS) is a group of IP networks run by one or
more network operators which has a single and clearly defined rout-
ing policy.
An AS has a unique number associated with it which is used both in
exchange of exterior routing information and as an identifier of the
AS itself. Exterior routing protocols such as BGP and EGP are used
to exchange routing information between ASes.
In routing terms an AS will normally use one or more interior gate-
way protocols (IGPs) in conjunction with some sort of common agreed
metrics when exchanging network information within its own AS.
The term AS is often confused or even misused as a convenient way of
grouping together a set of networks which belong under the same
administrative umbrella even if within that group of networks there
are various different routing policies. We provide the "community"
concept for such use. ASes can strictly have only one single rout-
ing policy.
The creation of an AS should be done in a conscious and well coordi-
nated manner to avoid creating ASes for the sake of it, perhaps
resulting in the worst case scenario of one AS per routing announce-
ment. It should be noted that there is a limited number of AS
numbers available. Also creating an AS may well increase the number
of AS paths modern EGPs will have to keep track of. This aggravates
what is known as "the routing table growth problem". This may mean
that by applying the general rules for the creation and allocation
of an AS below, some re-engineering may well be needed. However,
this may be the only way to actually implement the desired routing
policy anyway. The creation and allocation of an AS should be done
with the following recommendations in mind:
o Creation of an AS is only required when exchanging routing
information with other ASes. Some router implementations make
use of an AS number as a form of tagging to identify the rout-
ing process. However, it should be noted that this tag does
not need to be unique unless routing information is indeed
exchanged with other ASes.
o For a simple case of customer networks connected to a single
service provider, the IP network should normally be a member of
the service providers AS. In terms of routing policy the IP
network has exactly the same policy as the service provider and
there is no need to make any distinction in routing informa-
tion. This idea may at first seem slightly alien to some, but
it highlights the clear distinction in the use of the AS number
ripe-1nn.txt July, 1994
- 24 -
as a representation of routing policy as opposed to some form
of administrative use.
o If a network operator connects to more than one AS with dif-
ferent routing policies then they need to create their own AS.
In the case of multi-homed customer networks connected to two
service providers there are at least two different routing pol-
icies to a given customer network. At this point the customer
networks will be part of a single AS and this AS would be dis-
tinct from either of the service providers ASes. This allows
the customer the ability of having a different representation
of policy and preference to the different service providers.
This is the ONLY case where a network operator should create
its own AS number.
o As a general rule one should always try to populate the AS with
as many routes as possible, providing all routes conform to the
same routing policy.
Each AS is represented in the RIPE database by both an AS object and
the route objects representing the routes originated by the AS. The
AS object stores descriptive, administrative and contact information
about the AS as well as the routing policies of the AS in relation
to all neighbouring ASes.
The origin attributes of the route objects define the set of routes
originated by the AS. Each route object can have exactly one origin
attribute. Route objects can only be created and updated by the
"guardian" of the AS and not by those immediately responsible for
the particular routes referenced therein. This ensures that opera-
tors, especially service providers, remain in control of AS routing
announcements.
The AS object itself is used to represent a description of adminis-
trative details and the routing policies of the AS itself. The AS
object definition is depicted as follows.
ripe-1nn.txt July, 1994
- 25 -
Example:
aut-num: AS1104
descr: NIKHEF-H Autonomous system
as-in: from AS1213 100 accept AS1213
as-in: from AS1913 100 accept AS1913
as-in: from AS1755 150 accept ANY
as-out: to AS1213 announce ANY
as-out: to AS1913 announce ANY
as-out: to AS1755 announce AS1104 AS1913 AS1213
tech-c: Rob Blokzijl
admin-c: Eric Wassenaar
guardian: as-guardian(a)nikhef.nl
changed: ripe-dbm(a)ripe.net 920910
source: RIPE
See Appendix A for a complete syntax definition of the "aut-num"
object.
It should be noted that this representation provides two things:
o a set of routes.
o a description of administrative details and routing policies.
The set of routes can be used to generate network list based confi-
guration information as well as configuration information for exte-
rior routing protocols knowing about ASes. This means an AS can be
defined and is useful even if it does not use routing protocols
which know about the AS concept.
ripe-1nn.txt July, 1994
- 26 -
Description of local connections between ASes - "interas-
in/interas-out".
Often two ASes will have more than one physical connection between
them. In practice certain local policies my be placed on these
inter-AS connections as agreed by the two ASes. If we look at the
simple example below.
Example:
LINK1
+----------+
|a b|
AS1------AS2 AS3-----AS4
|c d|
+----------+
LINK2
It may be that AS2 prefers to get to AS3 on LINK1 (a and b being the
interface addresses of this link) and to AS4 on LINK2 (c and d being
the interface addresses of this link) with LINK2 as a backup for
AS3. Whilst this is purely of local information and at the AS level
will have no significance per se to any other ASes except AS2 and
AS3 this may be useful to represent. The way this is done is by
using the attributes "interas-in" and "interas-out". The exact syn-
tax is given in Appendix A. However, if we follow this example
through in terms of AS2 we would represent this policy as follows:
Example:
SYNTAX TO BE PROPOSED BY MERIT
Here we see additional local link based information in terms of the
IP addresses of the link (in this example represented by a and b and
c and d respectively). It should be noted that the preference on
interas-in attributes is only of relevance to other interas-in lines
and not to as-in lines. Of course this type on inter-AS policy
should always be bilaterally agreed to avoid asymmetry and in prac-
tice there may need to be corresponding interas-in attributes in the
policy representation of AS3. It should also be noted that there are
no interas-out attributes defined. In this case the general policy
is assumed.
The key difference between interas-in/interas-out and as-in/as-in
attributes is the former describes a local inter-AS policy and the
latter the general inter-AS policy as seen by other ASes. The gen-
eral policy should always be defined. The local inter-AS policy
should only be defined when such a policy really exists and the
ripe-1nn.txt July, 1994
- 27 -
implications of setting such policies is fully understood.
ripe-1nn.txt July, 1994
- 28 -
How to describe the exclusion policy of a certain AS - "as-exclude"
Some ASes have a routing policy based on the exclusion of certain
routes if for whatever reason a certain AS is used as transit.
Whilst, this is in general not good practice as it makes implicit
assumptions on topology with asymmetry a possible outcome if not
coordinated, this case needs to be accommodated within the routing
policy representation.
The way this is achieved is by making use of the "as-exclude" attri-
bute. The precise syntax of this attribute can be found in Appendix
A along with the rest of the defined syntax for the "aut-num"
object. However, some explanation of the use of this attribute is
useful. If we have the following example topology.
Example:
AS4--------AS3
| | |
| | |
AS1--------AS2--------AS5
With a simple corresponding policy like so:
Example:
aut-num: AS1
as-in: from AS2 100 accept ANY
as-out: to AS2 announce AS1
as-exclude: exclude AS4 to ANY
....
We see an interesting policy. What this says in simple terms is AS1
doesn't want to reach anything if it transit AS4. This can be a per-
fectly valid policy. However, it should be realised that for what-
ever reason AS2 decides to route to AS3 via AS4 then immediately AS1
has no connectivity to AS3 or if AS1 is running default to AS2 pack-
ets from AS1 will still flow via AS4. The important point about this
is that whilst AS1 can advise its neighbours of its policy it has no
direct control on how it can enforce this policy to neighbours
upstream.
Another interesting scenario to highlight the unexpected result of
using such an "as-exclude" policy. If we assume in the above example
AS2 preferred AS4 to reach AS3 and AS1 did not use default routing
then as stated AS1 would have no connectivity to AS3. Now lets sup-
pose that for example the link between AS2 and AS4 went down for
some reason. Like so:
ripe-1nn.txt July, 1994
- 29 -
Example:
AS4--------AS3
|
|
AS1--------AS2--------AS5
Suddenly AS1 now has connectivity to AS3. This unexpected behavior
should be considered when created policies based on the "as-exclude"
attribute.
The second problem with this type of policy is the potential of
asymmetry. In the original example we saw the correct policy from
AS1's point of view but if ASes with connectivity through AS4 do not
use a similar policy you have asymmetric traffic and policy. If an
AS uses such a policy they must be aware of the consequences of its
use. Namely that the specified routes which transit the AS (i.e.
routing announcements with this AS in the AS path information) in
question will be excluded. If not coordinated this can easily cause
asymmetry or even worse loss of connectivity to unknown ASes behind
(or in front for that matter) the transit AS in question. With this
in mind this attribute can only be viewed as a form of advisory to
other service providers. However, this does not preclude its use
with policy based tools if the attribute exists.
By having the ability to specify a route keyword based on any of the
four notations given in the syntax it allows the receiving AS to
specify what routes it wishes to exclude through a given transit AS
to a network granularity.
ripe-1nn.txt July, 1994
- 30 -
7. AS Macros
It may be difficult to keep track of each and every new AS that is
represented in the routing registry. A convenient way around this
is to define an `AS Macro' which essentially is a convenient way to
group ASes. This is done so that each and every AS guardian does not
have to add a new AS to it's routing policy as described by the as-
in and as-out attributes of it's AS object.
However, it should be noted that this creates an implicit trust on
the guardian of the AS-Macro.
An AS-Macro can be used in <routing policy expressions> for the
"as-in" and "as-out" attributes in the aut-num object. The AS-Macro
object is then used to derive the list or group of ASes.
A simple example would be something like:
Example:
aut-num: AS786
as-in: from AS1755 100 accept AS-EBONE AND NOT AS1104
as-in: from AS1755 100 accept AS-EBONE AND NOT AS1104
as-out to AS1755 announce AS786
.....
Where the as-macro object for AS-EBONE is as follows:
as-macro: AS-EBONE
descr: ASes routed by EBONE
as-list: AS2121 AS1104 AS2600 AS2122
as-list: AS1103 AS1755 AS2043
guardian: guardian(a)ebone.net
......
So the policy would be evaluated to:
aut-num: AS786
as-in: from AS1755 100 accept (AS2121 OR AS1104 OR AS2600 OR AS2122
as-in: from AS1755 100 accept AS1103 OR AS1755 OR AS2043) AND NOT AS1104
......
It should be noted that the above examples incorporates the rule for
line wrapping as defined in Appendix A for policy lines. See Appen-
dix C for a definition on the AS-Macro syntax.
ripe-1nn.txt July, 1994
- 31 -
8. The Community Object
A community is a group of routes that cannot be represented by an AS
or a group of ASes. It is in some circumstances useful to define a
group of routes that have something in common. This could be a spe-
cial access policy to a supercomputer centre, a group of routes used
for a specific mission, or a disciplinary group that is scattered
among several autonomous systems. Also these communities could be
useful to group routes for the purpose of network statistics.
Communities do not exchange routing information, since they do not
represent an autonomous system. More specifically, communities do
not define routing policies, but access or usage policies. However,
they can de used as in conjunction with an ASes routing policy to
define a set of routes the AS sets routing policy for.
Communities should be defined in a strict manner, to avoid creating
as many communities as there are routes, or even worse. Communities
should be defined following the two rules below;
o Communities must have a global meaning. Communities that have
no global meaning, are used only in a local environment and
should be avoided.
o Communities must not be defined to express non-local policies.
It should be avoided that a community is created because some
other organisation forces a policy upon your organisation.
Communities must only be defined to express a policy defined by
your organisation.
Community examples
There are some clear examples of communities:
BACKBONE -
all customers of a given backbone service provider even though
they can have various different routing policies and hence
belong to different ASes. This would be extremely useful for
statistics collection.
HEPNET -
the High Energy Physics community partly shares infrastructure
with other organisations, and the institutes it consists of are
scattered all over Europe, often being part of a non HEPNET
autonomous system. To allow statistics, access or part of a
routing policy , a community HEPNET, consisting of all routes
that are part of HEPNET, conveniently groups all these routes.
ripe-1nn.txt July, 1994
- 32 -
NSFNET -
the National Science Foundation Network imposes an acceptable
use policy on routes that wish to make use of it. A community
NSFNET could imply the set of routes that comply with this pol-
icy.
MULTI -
a large multinational corporation that does not have its own
internal infrastructure, but connects to the various parts of
its organisations by using local service providers that connect
them all together, may decide to define a community to restrict
access to their networks, only by networks that are part of
this community. This way a corporate network could be defined
on shared infrastructure. Also, this community could be used by
any of the service providers to do statistics for the whole of
the corporation, for instance to do topology or bandwidth plan-
ning.
Similar to Autonomous systems, each community is represented in the
RIPE database by both a community object and community tags on the
route objects representing the routes belonging to the community.
The community object stores descriptive, administrative and contact
information about the community.
The community tags on the route objects define the set of routes
belonging to a community. A route can have multiple community tags.
The community tags can only be created and updated by the "guardian"
of the community and not by those directly responsible for the par-
ticular network. This ensures that guardians remain in control of
community membership.
Here's an example of how this might be represented in terms of the
community tags within the network object. We have an example where
the route 192.16.199.0/24 has a single routing policy (i.e. that of
AS 1104), but is part of several different communities of interest.
We use the tag "comm-list" to represent the list of communities
associated with this route. NIKHEF-H uses the service provider
SURFNET (a service provider with customers with more than one rout-
ing policy), is also part of the High Energy Physics community as
well as having the ability to access the Supercomputer at CERN(4).
_________________________
(4) The community `CERN-SUPER', is somewhat national,
but is intended as an example of a possible use of an
access policy constraint.
ripe-1nn.txt July, 1994
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Example:
route: 192.16.199.0/24
descr: Local Ethernet
descr: NIKHEF section H
origin: AS1104
comm-list: HEPNET CERN-SUPER SURFNET
changed: ripe-dbm(a)ripe.net 920604
source: RIPE
In the above examples some communities have been defined. The com-
munity object itself will take the following format:
Example:
community: SURFNET
descr: Dutch academic research network
authority: SURFnet B.V.
guardian: comm-guardian(a)surfnet.nl
admin-c: Erik-Jan Bos
tech-c: Erik-Jan Bos
changed: ripe-dbm(a)ripe.net 920604
source: RIPE
For a complete explanation of the syntax please refer to Appendix B.
ripe-1nn.txt July, 1994
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9. Representation of Routing Policies
Routing policies of an AS are represented in the autonomous system
object. Initially we show some examples, so the reader is familiar
with the concept of how routing information is represented, used and
derived. Refer to Appendix A, for the full syntax of the "aut-num"
object.
The topology of routing exchanges is represented by listing how
routing information is exchanged with each neighbouring AS. This is
done separately for both incoming and outgoing routing information.
In order to provide backup and back door paths a relative cost is
associated with incoming routing information.
Example 1:
AS1------AS2
This specifies a simple routing exchange of two presumably isolated
ASes. Even if either of them has routing information about routes
in ASes other than AS1 and AS2, none of that will be announced to
the other.
aut-num: AS1
as-out: to AS2 announce AS1
as-in: from AS2 100 accept AS2
aut-num: AS2
as-out: to AS1 announce AS2
as-in: from AS1 100 accept AS1
The number 100 in the in-bound specifications is a relative cost,
which is used for backup and back door routes. The absolute value is
of no significance. The relation between different values within the
same AS object is. A lower value means a lower cost. This is cons-
ciously similar to the cost based preference scheme used with DNS MX
RRs.
Example 2:
Now suppose that AS2 is connected to one more AS, besides AS1, and
let's call that AS3:
AS1------AS2------AS3
ripe-1nn.txt July, 1994
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In this case there are two reasonable routing policies:
a) AS2 just wants to exchange traffic with both AS1 and AS3 itself
without passing traffic between AS1 and AS3.
b) AS2 is willing to pass traffic between AS3 and AS1, thus acting
as a transit AS
Example 2a:
In the first case AS1's representation in the routing registry will
remain unchanged as will be the part of AS2's representation
describing the routing exchange with AS1. A description of the addi-
tional routing exchange with AS3 will be added to AS2's representa-
tion:
aut-num: AS1
as-out: to AS2 announce AS1
as-in: from AS2 100 accept AS2
aut-num: AS2
as-out: to AS1 announce AS2
as-in: from AS1 100 accept AS1
as-out: to AS3 announce AS2
as-in: from AS3 100 accept AS3
aut-num: AS3
as-out: to AS2 announce AS3
as-in: from AS2 100 accept AS2
Note that in this example, AS2 keeps full control over its
resources. Even if AS3 and AS1 were to allow each others routes in
from AS2, the routing information would not flow because AS2 is not
announcing it(5).
Example 2b:
If contrary to the previous case, AS1 and AS3 are supposed to have
connectivity to each other via AS2, all AS objects have to change:
_________________________
(5) Of course AS1 and AS3 could just send traffic to
each other to AS2 even without AS2 announcing the
routes, hoping that AS2 will forward it correctly. Such
questionable practices however are beyond the scope of
this document.
ripe-1nn.txt July, 1994
- 36 -
aut-num: AS1
as-out: to AS2 announce AS1
as-in: from AS2 100 accept AS2 AS3
aut-num: AS2
as-out: to AS1 announce AS2 AS3
as-in: from AS1 100 accept AS1
as-out: to AS3 announce AS2 AS1
as-in: from AS3 100 accept AS3
aut-num: AS3
as-out: to AS2 announce AS3
as-in: from AS2 100 accept AS1 AS2
Note that the amount of routing information exchanged with a neigh-
bour AS is defined in terms of routes belonging to ASes. In BGP
terms this is the AS where the routing information originates and
the originating AS information carried in BGP could be used to
implement the desired policy. However, using BGP or the BGP AS-path
information is not required to implement the policies thus speci-
fied. Configurations based on route lists can easily be generated
from the database. The AS path information, provided by BGP can
then be used as an additional checking tool as desired.
The specification understands one special expression and this can be
expressed as a boolean expressions:
ANY - means any routing information known. For output this means
that all routes an AS knows about are announced. For input it
means that anything is accepted from the neighbour AS.
ripe-1nn.txt July, 1994
- 37 -
Example 3:
AS4 is a stub customer AS, which only talks to service provider
AS123.
|
|
-----AS123------AS4
|
|
aut-num: AS4
as-out: to AS123 announce AS4
as-in: from AS123 100 accept ANY
aut-num: AS123
as-in: from AS4 100 accept AS4
as-out: to AS4 announce ANY
<further neighbours>
Since AS4 has no other way to reach the outside world than AS123 it
is not strictly necessary for AS123 to send routing information to
AS4. AS4 can simply send all traffic for which it has no explicit
routing information to AS123 by default. This strategy is called
default routing. It is expressed in the routing registry by adding
one or more default tags to the autonomous system which uses this
strategy. In the example above this would look like:
aut-num: AS4
as-out: to AS123 announce AS4
default: AS123 100
aut-num: AS123
as-in: from AS4 100 accept AS4
<further neighbours>
ripe-1nn.txt July, 1994
- 38 -
Example 4:
AS4 now connects to a different operator, AS5. AS5 uses AS123 for
outside connectivity but has itself no direct connection to AS123.
AS5 traffic to and from AS123 thus has to pass AS4. AS4 agrees to
act as a transit AS for this traffic.
|
|
-----AS123------AS4-------AS5
|
|
aut-num: AS4
as-out: to AS123 announce AS4 AS5
as-in: from AS123 100 accept ANY
as-out: to AS5 announce ANY
as-in: from AS5 50 accept AS5
aut-num: AS5
as-in: from AS4 100 accept ANY
as-out: to AS4 announce AS5
aut-num: AS123
as-in: from AS4 100 accept AS4 AS5
as-out: to AS4 announce ANY
<further neighbours>
Now AS4 has two sources of external routing information. AS5 which
provides only information about its own routes and AS123 which pro-
vides information about the external world. Note that AS4 accepts
information about AS5 from both AS123 and AS5 although AS5 informa-
tion cannot come from AS123 since AS5 is connected only via AS4
itself. The lower cost of 50 for the announcement from AS5 itself
compared to 100 from AS123 ensures that AS5 is still believed even
in case AS123 will unexpectedly announce AS5.
In this example too, default routing can be used by AS5 much like in
the previous example. AS4 can also use default routing towards
AS123:
ripe-1nn.txt July, 1994
- 39 -
aut-num: AS4
as-out: to AS123 announce AS4 AS5
default: AS123 11
as-in: from AS5 50 accept AS5
Note no announcements to AS5, they default to us.
aut-num: AS5
as-out: to AS4 announce AS5
default: AS4 100
aut-num: AS123
as-in: from AS4 100 announce AS4 AS5
<further neighbours>
Note that the relative cost associated with default routing is
totally separate from the relative cost associated with in-bound
announcements. The default route will never be taken if an explicit
route is known to the destination. Thus an explicit route can never
have a higher cost than the default route. The relative cost asso-
ciated with the default route is only useful in those cases where
one wants to configure multiple default routes for redundancy.
Note also that in this example the configuration using default
routes has a subtly different behavior than the one with explicit
routes: In case the AS4-AS5 link fails AS4 will send traffic to AS5
to AS123 when using the default configuration. Normally this makes
not much difference as there will be no answer and thus little
traffic. With certain datagram applications which do not require
acknowledgments however, significant amounts of traffic may be use-
lessly directed at AS123. Similarly default routing should not be
used if there are stringent security policies which proscribe any
traffic intended for AS5 to ever touch AS123.
Generally it can be said that default routing should only be used in
very simple topologies. Once the situation gets more complex using
default routes can lead to unexpected results or even defeat the
routing policies established when links fail. As an example consider
how Example 5a) below could be implemented using default routing.
ripe-1nn.txt July, 1994
- 40 -
Example 5:
In a different example AS4 has a private connection to AS6 which in
turn is connected to the service provider AS123:
|
|
-----AS123------AS4
| |
| |
| |
AS6 ---------+
There are a number of policies worth examining in this case:
a) AS4 and AS6 wish to exchange traffic between themselves
exclusively via the private link between themselves; such
traffic should never pass through the backbone (AS123). The
link should never be used for transit traffic, i.e. traffic not
both originating in and destined for AS4 and AS6.
b) AS4 and AS6 wish to exchange traffic between themselves via the
private link between themselves. Should the link fail, traffic
between AS4 and AS6 should be routed via AS123. The link
should never be used for transit traffic.
c) AS4 and AS6 wish to exchange traffic between themselves via the
private link between themselves. Should the link fail, traffic
between AS4 and AS6 should be routed via AS123. Should the
connection between AS4 and AS123 fail, traffic from AS4 to des-
tinations behind AS123 can pass through the private link and
AS6's connection to AS123.
d) AS4 and AS6 wish to exchange traffic between themselves via the
private link between themselves. Should the link fail, traffic
between AS4 and AS6 should be routed via AS123. Should the
backbone connection of either AS4 or AS6 fail, the traffic of
the disconnected AS should flow via the other AS's backbone
connection.
ripe-1nn.txt July, 1994
- 41 -
Example 5a:
aut-num: AS4
as-in: from AS123 100 accept NOT AS6
as-out: to AS123 announce AS4
as-in: from AS6 50 accept AS6
as-out: to AS6 announce AS4
aut-num: AS123
as-in: from AS4 100 accept AS4
as-out: to AS4 announce ANY
as-in: from AS6 100 accept AS6
as-out: to AS6 announce ANY
<further neighbours>
aut-num: AS6
as-in: from AS123 100 accept NOT AS4
as-out: to AS123 announce AS6
as-in: from AS4 50 accept AS4
as-out: to AS4 announce AS6
Note that here the configuration is slightly inconsistent. AS123
will announce AS6 to AS4 and AS4 to AS6. These announcements will be
filtered out on the receiving end. This will implement the desired
policy. Consistency checking tools might flag these cases however.
ripe-1nn.txt July, 1994
- 42 -
Example 5b:
aut-num: AS4
as-in: from AS123 100 accept ANY
as-out: to AS123 announce AS4
as-in: from AS6 50 accept AS6
as-out: AS6 AS4
aut-num: AS123
as-in: AS4 100 AS4
as-out: AS4 ANY
as-in: AS6 100 AS6
as-out: AS6 ANY
<further neighbours>
aut-num: AS6
as-in: from AS123 100 accept ANY
as-out: to AS123 announce AS6
as-in: from AS4 50 accept AS4
as-out: to AS4 announce AS6
The thing to note here is that in the ideal operational case, `all
links working' AS4 will receive announcements for AS6 from both
AS123 and AS6 itself. In this case the announcement from AS6 will
be preferred because of its lower cost and thus the private link
will be used as desired. AS6 is configured as a mirror image.
ripe-1nn.txt July, 1994
- 43 -
Example 5c:
The new feature here is that should the connection between AS4 and
AS123 fail, traffic from AS4 to destinations behind AS123 can pass
through the private link and AS6's connection to AS123.
aut-num: AS4
as-in: from AS123 100 accept ANY
as-out: to AS123 announce AS4
as-in: from AS6 50 accept AS6
as-in: from AS6 110 accept ANY
as-out: to AS6 AS4
aut-num: AS123
as-in: from AS4 1 accept AS4
as-out: to AS4 announce ANY
as-in: from AS6 1 accept AS6
as-in: from AS6 2 accept AS4
as-out: to AS6 announce ANY
<further neighbours>
aut-num: AS6
as-in: from AS123 100 accept ANY
as-out: to AS123 AS6 announce AS4
as-in: from AS4 50 accept AS4
as-out: to AS4 announce ANY
Note that it is important to make sure to propagate routing informa-
tion for both directions in backup situations like this. Connec-
tivity in just one direction is not useful at all for almost all
applications.
Note also that in case the AS6-AS123 connection breaks, AS6 will
only be able to talk to AS4. The symmetrical case (5d) is left as an
exercise to the reader.
10. Future Extensions
We envision that over time the requirements for describing routing
policy will evolve. The routing protocols will evolve to support the
requirements and the routing policy description syntax will need to
evolve as well. For that purpose, a separate document will describe
experimental syntax definitions for policy description. This docu-
ment will be updated when new objects or attributes are proposed or
modified.
Two new attributes of the AS object which are proposed and supported
by the Merit Routing Registry are as-transit and db-selector.
as-transit describes the transit preferences of an AS. It allows an
AS to describe its path preference in order to reach certain
ripe-1nn.txt July, 1994
- 44 -
destinations. The AS(s) specified in the path preference may or may
not be an immediate neighbor of the AS defined in the AS object.
as-transit accommodates policy decisions involving AS path whereas
as-in and as-out do not. It is not unusual for ASs to have routing
policies which involve path selection based on AS. Emerging proto-
cols like SDRP [13] will allow an AS to choose a path independent of
a neighboring ASs path choice. as-transit permits descriptions based
on AS path selection.
The DataBase Selector (db-selector) function allows one to take
advantage of information registered in other Registries. It permits
the selection of networks in a database based on their attributes.
It is proposed to be used within the as-in/as-out attribute family
to make the description of policy concise. For example, if an AS
has the policy of not accepting any routes from country XYZ, the AS
can use the db-selector to check a database which has a network and
country attribute and relate that information to the information in
the routing registry. The advantage of referencing another database
is that the routing registry will avoid duplicating the information
maintained in other information registries.
Detailed examples and syntax are described in document ???? [14].
ripe-1nn.txt July, 1994
- 45 -
11. References
[1] Bates, T., Jouanigot, J-M., Karrenberg, D., Lothberg, P.,
Terpstra, M., "Representation of IP Routing Policies in the
RIPE Database", RIPE-81, February 1993.
[2] Merit Network Inc.,"Representation of Complex Routing Policies
of an Autonomous System", DRAFT, March, 1994.
[3] PRIDE Tools Release 1.
See ftp.ripe.net:pride/tools/pride-tools-1.tar.Z.
[4] Merit Inc. RRDB Tools.
See rrdb.merit.edu:pub/meritrr/*
[5] The Network List Compiler.
See dxcoms.cern.ch:pub/ripe-routing-wg/nlc-2.2d.tar
[6] Lord, A., Terpstra, M., "RIPE Database Template for Networks
and Persons", DRAFT, May 1994.
[7] Karrenberg, D., "RIPE Database Template for Domains", RIPE-49,
April 1992.
[8] Lougheed, K., Rekhter, Y., "A Border Gateway Protocol 3 (BGP-
3)", RFC1267, October 1991.
[9] Rekhter, Y., Li, T., "A Border Gateway Protocol 4 (BGP-4)",
INTERNET-DRAFT, draft-ietf-bgp-bgp4-10.txt, May 1994.
[10] Bates, T., Karrenberg, D., Terpstra, M., "Support for Classless
Internet Addresses in the RIPE Database", DRAFT, May 1994.
[11] Karrenberg, D., "Authorisation and Notification of Changes in
the RIPE Database", RIPE-96, October 1993.
[12] Bates, T., "Support of Guarded fields within the RIPE Data-
base", ripe-108, February 1994.
[13] Estrin, D., Li, T., Rekhter, Y., Varadhan, K., "Source Demand
Routing: Packet Format and Forwarding Specification (Version
1)", INTERNET-DRAFT, draft-ietf-sdr-sdrp-04.txt, March 1994.
[14] ?????, "Experimental Objects and attributes for the Routing
Registry, ???, ????.
ripe-1nn.txt July, 1994
- 46 -
12. Author's Addresses
Tony Bates
RARE/PRIDE Project
c/o RIPE Network Coordination Centre
Kruislaan 409
NL-1098 SJ Amsterdam
The Netherlands
+31 20 592 5064
T.Bates(a)ripe.net
Elise Gerich
The University of Michigan
Merit Computer Network
1075 Beal Avenue
Ann Arbor, MI 48109
USA
+1 313 936 2120
epg(a)merit.edu
Laurent Joncheray
The University of Michigan
Merit Computer Network
1075 Beal Avenue
Ann Arbor, MI 48109
USA
+1 313 936 2065
lpj(a)merit.edu
Jean-Michel Jouanigot
CERN, European Laboratory for Particle Physics
CH-1211 Geneva 23
Switzerland
+41 22 767 4417
Jean-Michel.Jouanigot(a)cern.ch
Daniel Karrenberg
RIPE Network Coordination Centre
Kruislaan 409
NL-1098 SJ Amsterdam
The Netherlands
+31 20 592 5065
D.Karrenberg(a)ripe.net
ripe-1nn.txt July, 1994
- 47 -
Marten Terpstra
PRIDE Project
c/o RIPE Network Coordination Centre
Kruislaan 409
NL-1098 SJ Amsterdam
The Netherlands
+31 20 592 5064
M.Terpstra(a)ripe.net
Jessica Yu
The University of Michigan
Merit Computer Network
1075 Beal Avenue
Ann Arbor, MI 48109
USA
+1 313 936 2655
jyy(a)merit.edu
ripe-1nn.txt July, 1994
- 48 -
Appendix A - Syntax for the aut-num object.
Here is a summary of the tags associated with aut-num object itself
and their status. The first column specifies the attribute, the
second column whether this attribute is mandatory in the aut-num
object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
aut-num: [mandatory] [single]
descr: [mandatory] [multiple]
as-in: [optional] [multiple]
as-out: [optional] [multiple]
interas-in: [optional] [multiple]
interas-out: [optional] [multiple]
as-exclude: [optional] [multiple]
default: [optional] [multiple]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
guardian: [mandatory] [single]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
aut-num:
The autonomous system number. This must be a uniquely allo-
cated autonomous system number from an AS registry (i.e. the
RIPE NCC, the Inter-NIC, etc).
Format:
AS<positive integer between 1 and 65535>
Example:
aut-num: AS1104
Status: mandatory, only one line allowed
descr:
A short description of the Autonomous System.
Format:
free text
Status: mandatory, multiple lines allowed
as-in:
ripe-1nn.txt July, 1994
- 49 -
Example:
descr: NIKHEF section H
descr: Science Park Watergraafsmeer
descr: Amsterdam
A description of accepted routing information between AS peers.
Format:
from <aut-num> <cost> accept <routing policy expression>
The keywords from and accept are optional and can be omit-
ted.
<aut-num> refers to your AS neighbour.
<cost> is a positive integer used to express a relative
cost of routes learned. The lower the cost the more pre-
ferred the route.
<routing policy expression> can take the following for-
mats.
1. A list of one or more ASes, AS Macros, Communities or
Network Lists.
A Network List is a list of network numbers in prefix
length format, separated by commas, and surrounded by
curly brackets.
Examples:
as-in: from AS1103 100 accept AS1103
as-in: from AS786 105 accept AS1103
as-in: from AS786 10 accept AS786 HEPNET
as-in: from AS1755 110 accept AS1103 AS786
as-in: from AS3333 100 accept {192.87.45.0/16, 128.141.0.0/16}
2. A set of KEYWORDS. The following KEYWORD is
currently defined:
ANY this means anything the neighbour AS knows.
3. A logical expression of either 1 or 2 above The
current logical operators are defined as:
AND
OR
NOT
ripe-1nn.txt July, 1994
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NOTE: if no logical operator is given between ASes,
AS-macros, Communities, Network Lists and KEYWORDS it
is implicitly evaluated as an `OR' operation. The OR
can be left out for conciseness.
Rules are grouped together using parenthesis i.e "("
and ")".
Example:
as-in: from AS1755 100 accept ANY AND NOT (AS1234 OR AS513)
as-in: from AS1755 150 accept AS1234 OR {35.0.0.0/8}
A rule can be wrapped over lines providing the
associated <aut-num>, <cost> values and from and
accept keywords are repeated and occur on con-
secutive lines.
Example:
as-in: from AS1755 100 accept ANY AND NOT (AS1234 AS513)
and
as-in: from AS1755 100 accept ANY AND NOT (
as-in: from AS1755 100 accept AS1234 AS513)
are evaluated to the same result. Please note
that the ordering of these continuing lines
matters.
Status: optional, multiple lines allowed
as-out:
A description of generated routing information sent to other AS
peers.
Format:
to <aut-num> announce <routing policy expression
The to and announce keywords are optional and can be omit-
ted.
<aut-num> refers to your AS neighbour.
<routing policy expression> is explained in the as-in
attribute definition above.
Example:
as-out: to AS1104 announce AS978
as-out: to AS1755 announce ANY
as-out: to AS786 announce ANY AND NOT (AS978)
Status: optional, multiple lines allowed
ripe-1nn.txt July, 1994
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interas-in:
STILL TO BE PROPOSED BY MERIT
Status: optional, multiple lines allowed
interas-out:
STILL TO BE PROPOSED BY MERIT
Status: optional, multiple lines allowed
as-exclude:
A list of transit ASes to ignore all routes from.
Format:
exclude <aut-num> to <exclude-route-keyword>
Keywords exclude and to are optional and can again be
omitted.
<aut-num> refers to the transit AS in question.
an <exclude-route-keyword> can be ONE of the following.
1. <aut-num>
2. AS macro
3. Community
4. ANY
Examples:
as-exclude: exclude AS690 to HEPNET
This means exclude any HEPNET routes which have a route
via AS690.
as-exclude: exclude AS1800 to AS-EUNET
This means exclude any AS-EUNET routes which have a route
via AS1800.
as-exclude: exclude AS1755 to AS1104
This means exclude any AS1104 route which have a route via
AS1755.
as-exclude: exclude AS1104 to ANY
This means exclude all routes which have a route via
ripe-1nn.txt July, 1994
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AS1104.
Status: optional, multiple lines allowed
default:
An indication of how default routing is done.
Format:
<aut-num> <relative cost> <default-expression>
where <aut-num> is the AS peer you will default route to,
and <relative cost> is the relative cost is a positive
integer used to express a preference for default. There is
no relationship to the cost used in the as-in tag. The AS
peer with the lowest cost is used for default over ones
with higher costs.
<default-expression> is optional and provides information
on how a default route is selected. It can take the fol-
lowing formats:
1. static. This indicates that a default is statically
configured to this AS peer.
2. A network list with the syntax as described in the
as-in attribute. This indicates that this list of
routes is used to generate a default route. A special
but valid value in this is the special route used by
some routing protocols to indicate default: 0.0.0.0/0
3. default. This is the same as {0.0.0.0/0}. This means
that the routing protocol between these two peers
generates a true default.
Examples:
default: AS1755 10
default: AS786 5 {140.222.0.0/16, 192.87.45.0/24}
default: AS2043 15 default
Status: optional, multiple lines allowed
tech-c:
Full name or uniquely assigned NIC-handle of a technical con-
tact person. This is someone to be contacted for technical
problems such as misconfiguration.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
ripe-1nn.txt July, 1994
- 53 -
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person. In many cases this would be the name of the
guardian.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
admin-c: Joe T Bloggs
admin-c: JTB1
Status: mandatory, multiple lines allowed
guardian:
Mailbox of the guardian of the Autonomous system.
Format:
<email-address>
The <email-address> should be in RFC822 domain format
wherever possible.
Example:
guardian: as1104-guardian(a)nikhef.nl
Status: mandatory, only one line and e-mail address allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: Multihomed AS talking to AS1755 and AS786
remarks: Will soon connect to AS1104 also.
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be sent. See also
[11].
ripe-1nn.txt July, 1994
- 54 -
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 55 -
Appendix B - Syntax details for the community object.
Here is a summary of the tags associated with community object
itself and their status. The first column specifies the attribute,
the second column whether this attribute is mandatory in the commun-
ity object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
community: [mandatory] [single]
descr: [mandatory] [multiple]
authority: [mandatory] [single]
guardian: [mandatory] [single]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
community:
Name of the community. The name of the community should be
descriptive of the community it describes.
Format:
Upper case text string which cannot start with "AS" or any
of the <routing policy expression> KEYWORDS. See Appendix
A.
Example:
community: WCW
Status: mandatory, only one line allowed
descr:
A short description of the community represented.
Format:
free text
Example:
descr: Science Park Watergraafsmeer
descr: Amsterdam
Status: mandatory, multiple lines allowed
ripe-1nn.txt July, 1994
- 56 -
authority:
The formal authority for this community. This could be an
organisation, institute, committee, etc.
Format:
free text
Example:
authority: WCW LAN Committee
Status: mandatory, only one line allowed
guardian:
Mailbox of the guardian of the community.
Format:
<email-address>
The <email-address> should be in RFC822 domain format
wherever possible.
Example:
guardian: wcw-guardian(a)nikhef.nl
Status: mandatory, only one line and email address allowed
tech-c:
Full name or uniquely assigned NIC-handle of an technical con-
tact person for this community.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person. In many cases this would be the name of the
guardian.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Example:
admin-c: Joe T Bloggs
admin-c: JTB1
ripe-1nn.txt July, 1994
- 57 -
Status: mandatory, multiple lines allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: Temporary community
remarks: Will be removed after split into ASes
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
ripe-1nn.txt July, 1994
- 58 -
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 59 -
Appendix C - AS Macros syntax definition.
Here is a summary of the tags associated with as-macro object itself
and their status. The first column specifies the attribute, the
second column whether this attribute is mandatory in the as-macro
object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
as-macro: [mandatory] [single]
descr: [mandatory] [multiple]
as-list: [mandatory] [multiple]
guardian: [mandatory] [single]
tech-c: [mandatory] [multiple]
admin-c: [mandatory] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
as-macro:
The name of a macro containing at least two Autonomous Systems
grouped together for ease of administration.
Format:
AS-<string>
The <string> should be in upper case and not contain any
special characters.
Example:
as-macro: AS-EBONE
Status: mandatory, only one line allowed
descr:
A short description of the Autonomous System Macro.
Format:
free text
Example:
descr: Macro for EBONE connected ASes
Status: mandatory, multiple lines allowed
ripe-1nn.txt July, 1994
- 60 -
as-list:
The list of ASes that make up this macro.
Format:
<aut-num> <aut-num> ...
See Appendix A for <aut-num> definition.
Example:
as-list: AS786 AS513 AS1104
Status: mandatory, multiple lines allowed
guardian:
Mailbox of the guardian of this AS macro.
Format:
<email-address>
The <email-address> should be in RFC822 domain format
wherever possible.
Example:
guardian: as-ebone-guardian(a)ebone.net
Status: mandatory, only one line and e-mail address allowed
tech-c:
Full name or uniquely assigned NIC-handle of a technical con-
tact person for this macro. This is someone to be contacted for
technical problems such as misconfiguration.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Examples:
tech-c: John E Doe
tech-c: JED31
Status: mandatory, multiple lines allowed
admin-c:
Full name or uniquely assigned NIC-handle of an administrative
contact person. In many cases this would be the name of the
guardian.
Format:
<firstname> <initials> <lastname> or <nic-handle>
Examples:
ripe-1nn.txt July, 1994
- 61 -
admin-c: Joe T Bloggs
admin-c: JTB1
Status: mandatory, multiple lines allowed
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: AS321 will be removed from this Macro shortly
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
ripe-1nn.txt July, 1994
- 62 -
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 63 -
Appendix D - Syntax for the "route" object.
There is a summary of the tags associated with community object
itself and their status. The first column specifies the attribute,
the second column whether this attribute is mandatory in the commun-
ity object, and the third column whether this specific attribute can
occur only once per object [single], or more than once [multiple].
When specifying multiple lines per attribute, the attribute name
must be repeated. See [6] the example for the descr: attribute.
route: [mandatory] [single]
descr: [mandatory] [multiple]
origin: [mandatory] [single]
hole: [optional] [multiple]
withdrawn: [optional] [multiple]
comm-list: [optional] [multiple]
remarks: [optional] [multiple]
notify: [optional] [multiple]
maintainer: [optional] [single]
changed: [mandatory] [multiple]
source: [mandatory] [single]
Each attribute has the following syntax:
route:
Route being announced.
Format:
Classless representation of a route with the RIPE database
known as the "prefix length" representation. See [10] for
more details on classless representations.
Examples:
route: 192.87.45.0/24
This represents addressable bits 192.87.45.0 to
192.87.45.255.
route: 192.1.128.0/17
This represents addressable bits 192.1.128.0 to
192.1.255.255.
Status: mandatory, only one line allowed
origin:
The autonomous system announcing this route.
Format:
<aut-num>
ripe-1nn.txt July, 1994
- 64 -
See appendix A for <aut-num> syntax.
Example:
origin: AS1104
Status: mandatory, only one line allowed
hole:
Denote the parts of the address space covered this route object
to which the originator does not provide connectivity.
Format:
Classless representation of a route with the RIPE database
known as the "prefix length" representation. See [10] for
more details on classless representations. It should be
noted that is sub-aggregate must be a component of that
registered in the route object.
Example:
hole: 193.0.4.0/24
Status: optional, multiple lines allowed
withdrawn:
Used to denote the day this route has been withdrawn from the
Internet routing mesh. It should be noted that this date cannot
be in the future.
Format:
YYMMDD
YYMMDD denotes the date this route was withdrawn.
Example:
withdrawn: 940711
Status: optional, multiple lines allowed
comm-list:
List of one or more communities this route is part of.
Format:
<community> <community> ...
See Appendix B for <community> definition.
Example:
comm-list: HEP LEP
Status: optional, multiple lines allowed
ripe-1nn.txt July, 1994
- 65 -
remarks:
Remarks/comments, to be used only for clarification.
Format:
free text
Example:
remarks: Multihomed AS talking to AS1755 and AS786
remarks: Will soon connect to AS1104 also.
Status: optional, multiple lines allowed
notify:
The notify attribute contains an email address to which notifi-
cations of changes to this object should be send. See also
[11].
Format:
<email-address>
The <email-address> should be in RFC822 domain syntax
wherever possible.
Example:
notify: Marten.Terpstra(a)ripe.net
Status: optional, multiple lines allowed
maintainer:
The maintainer attribute contains a registered maintainer name.
See also [11].
Format:
<registered maintainer name>
Example:
maintainer: RIPE-DBM
Status: optional, multiple lines allowed
changed:
Who changed this object last, and when was this change made.
Format:
<email-address> YYMMDD
<email-address> should be the address of the person who
made the last change. YYMMDD denotes the date this change
was made.
Example:
ripe-1nn.txt July, 1994
- 66 -
changed: johndoe(a)terabit-labs.nn 900401
Status: mandatory, multiple lines allowed
source:
Source of the information.
This is used to separate information from different sources
kept by the same database software. For RIPE database entries
the value is fixed to RIPE.
Format:
RIPE
Status: mandatory, only one line allowed
ripe-1nn.txt July, 1994
- 67 -
Appendix E - List of reserved words
The following list of words are reserved for use within the attri-
butes of the AS object. The use of these words is solely for the
purpose of clarity. All keywords must be lower case.
accept
announce
exclude
from
to
transit
Examples of the usage of the reserved words are:
as-in: from neighborAS accept route
as-out: to neighborAS announce route
as-exclude: exclude ASpath to destination
as-transit: transit ASpath to destination
default: from neighborAS accept route
default: to neighborAS announce route
Note: that as-transit is an experimental attribute. See section 10.
ripe-1nn.txt July, 1994
- 68 -
Appendix F - Motivations for RIPE-81++
This appendix gives motivations for the major changes in this propo-
sal from ripe-81. (It is not complete yet).
The main goals of the routing registry rework are:
SPLIT
Separate the allocation and routing registry functions into
different database objects. This will facilitate data manage-
ment if the Internet registry and routing registry functions
are separated (like in other parts of the world). It will also
make more clear what is part of the routing registry and who
has authority to change allocation vs. routing data.
CIDR
Add the possibility to specify classless routes in the routing
registry. Classless routes are being used in Internet produc-
tion now. Aggregation information in the routing registry is
necessary for network layer troubleshooting. It is also neces-
sary because aggregation influences routing policies directly.
CALLOC
Add the possibility to allocate address space on classless
boundaries in the allocation registry. This is a way to
preserve address space.
CLEAN
To clean up some of the obsolete and unused parts of the rout-
ing registry.
The major changes are now discussed in turn:
Introduce Classless Addresses
CIDR, CALLOC
Introduce route object.
SPLIT, CIDR and CALLOC.
Delete obsolete attributes from inetnum.
CLEAN.
ripe-1nn.txt July, 1994
- 69 -
Delete RIPE-DB and LOCAL from routing policy expressions.
CLEAN
Allow multiple ASes to originate the same route
Because it is being done. CIDR. Made possible by SPLIT.
ripe-1nn.txt July, 1994
- 70 -
Appendix G - Transition strategy from RIPE-81 to RIPE-81++
Transition from the routing registry described by ripe-81 to the
routing registry described in this document is a straightforward
process once the new registry functions have been implemented in the
database software and are understood by the most commonly used
registry tools. The routing related attributes in the classful inet-
num objects of ripe-81 can be directly translated into new routing
objects. Then these attributes can be deleted from the inetnum
object making that object conform to the new schema.
Proposed transition steps:
1) Implement classless addresses and new object definition in the
database software.
2) Make common tools understand the new schema and prefer it if
both old and new are present.
3) Invite everyone to convert their data to the new format. This
can be encouraged by doing conversions automatically and pro-
posing them to maintainers.
4) At a flag day remove all remaining routing information from the
inetnum objects. Before the flag day all usage of obsoleted
inetnum attributes has to cease and all other routing registry
functions have to be taken over by the new objects and attri-
butes.
The current estimate is that point three can be reached in the Sum-
mer 1994 if the draft is accepted by mid-June. The flag day should
be scheduled 3-4 months after this point.
ripe-1nn.txt July, 1994
2
1
DB group,
please note that next Tuesday I plan to send out an update to
ripe-108. This represents little change except that in the future
automatic block splitting will not be done by the guarded field
process. This is being put in place becuase of the way we're implementing the
classless database. I am sending the draft below for any immediate
reactions before it gets a ripe number and is sent to all guardians.
The only real change is in Section 4 which details the difference from
now and the future. It provides an example of how an object can be
split. We realise the implication this will have in that the guardian
must liaise with the object registrar but this is something
we cannot avoid. There are of course plans for alternate guardian
mechanims in the future. It should also be noted that as we move
toward RIPE-81++ in production this document will undoubtably change again.
If you are interested in the details as to why we need to make this
change please send a mail to either marten or myself.
It should also be noted that whilst we will not start this technique
as of Tuesday we will be encouraging all guardians to follow the
"exact match" technique as soon as possible.
Regards,
--Tony.
Support of Guarded fields within the RIPE Database
Tony Bates
Document-ID: ripe-???
Obsoletes: ripe-108
Status: DRAFT
1. Introduction
The RIPE database contains several significant attributes which make
it well suited for use as part of operational procedures and confi-
guration. Most significantly are the attributes which make up the
RIPE Routing Registry (RR) as specified in RIPE-81 [1][2], namely
the "aut-sys" and "comm-list" attributes. For these attributes to
be of use to service providers they must be:
o Properly authorised.
o Efficient for both maintainers of the attributes and the main-
tainers of the whole database.
This document describes an overview of the RIPE database attributes
which are guarded, the procedure for updating these guarded attri-
butes and the general use of "guarded" fields within the RIPE data-
base. It should be noted that this document is an update of the ori-
ginal document, ripe-108 [5]. The significant change is section 4
which provides details of the exact matching algorithm now used for
updating objects. This is a change from the original method used in
ripe-108.
2. The Database Guarded Attributes
All the guarded attributes currently supported in the RIPE database
are contained within the "inetnum" or network object. However, the
association corresponds to their relevant guarded database objects.
If we look at a simple example this becomes clear:
ripe-???.txt 11th July, 1994
- 2 -
inetnum: 192.87.45.0
netname: RIPE-NCC
descr: RIPE Network Coordination Centre
descr: Amsterdam, Netherlands
country: NL
admin-c: Daniel Karrenberg
tech-c: Marten Terpstra
connect: RIPE NSF WCW
aut-sys: AS1104
comm-list: SURFNET
ias-int: 192.87.45.80 AS1104
ias-int: 192.87.45.6 AS2122
ias-int: 192.87.45.254 AS2600
rev-srv: ns.ripe.net
rev-srv: ns.eu.net
notify: ops(a)ripe.net
changed: tony(a)ripe.net 940110
source: RIPE
This shows that the RIPE-NCC network belongs to autonomous system
1104 and is in a community known as SURFNET. This is valuable infor-
mation that could easily be used for example for routing policy pur-
poses (as well as other operational uses). Currently support for the
following set of guarded attributes is implemented:
aut-sys
The "aut-sys" attribute has a direct mapping to "aut-num"
objects as defined in RIPE-81. That is the Autonomous System
(AS) that the network number is a part of. As defined in RIPE-
81, a network can only belong to one AS and hence the "aut-sys"
attribute can only contain one AS number. The syntax of the
"aut-sys" attribute is:
AS<positive integer between 1 and 65535> (1). i.e. AS1104
comm-list
The "comm-list" attribute has a direct mapping to "community"
objects as defined in RIPE-81. A network can belong to more
than one community. The syntax of "comm-list" is:
Multiple text strings which cannot start with "AS" or any of
the <routing policy expression> KEYWORDS defined in RIPE-81.
_________________________
(1) This represents a change from RIPE-50 [3] where
the "aut-sys" attribute was defined to be a positive
integer only, not containing the string "AS" at the
start. This change has been made to be consistent with
the "aut-num" object syntax.
ripe-???.txt 11th July, 1994
- 3 -
As these attributes are tightly coupled to their associated objects
it makes sense for these attributes to be updated not by the network
maintainer but by the maintainer of the referenced object(s). The
basic premise behind this is that these attributes should be used
for various operational procedures such as setting routing policy,
accounting and so on. For these attributes to be used by network
operators for day to day operations they need to be guarded in such
a way that can be trusted and are guaranteed to be unique - with any
conflicts quickly and easily resolved. The procedure for achieving
this is detailed below.
3. The Basic Procedure
For each of the guarded attributes detailed above, a list of all
networks having this attribute is kept separately from the general
database itself. These lists (also called `guarded files') will be
maintained and be served as the `only' source of membership informa-
tion used in the database. Normal database updates `never' change
these attributes. If an update includes such an attribute and a
discrepancy between the values in the update and those in the data-
base is found, a diagnostic message will be sent to the originator
of the update and the guarded value(s) will not be affected. The
attributes as defined in these files are incorporated in the data-
base once a day. To ensure proper control and authorisation, these
lists will be maintained at the RIPE NCC on the same machine that
contains the RIPE database. The "guardians" of the corresponding
database objects will have to maintain their own guarded files. The
guardians are provided with individually assigned login accounts at
the RIPE NCC. The guardians can themselves decide in what manner
they want to update their file. The NCC will offer interactive
logins, ftp logins or any other means that might be deemed useful.
3.1. Some Details
As stated each guardian will be issued with an account on the cen-
tral NCC machine known as `guardian.ripe.net'. This account will
contain a `restricted' environment which will allow the guardian of
the relevant object to update their associated guardian file (2).
Wherever possible the account name issued to the guardian will be
the same as the object name.
For example, the guardian of the AS1104 aut-num object will receive
an account known as "AS1104". With each guardian account the
corresponding file will be parsed at each update run (once a day).
This file will contain the list on networks associated with the
object. See appendix A for details of the format and syntax of the
guardian files.
_________________________
(2) As stated, the mechanism for updating the guardi-
an file will initially be by interactive login or file
transfer. However, this doesn't preclude other mechan-
isms in the future.
ripe-???.txt 11th July, 1994
- 4 -
A tool will also be provided within the restricted environment to
syntax check the guarded file to avoid against possible typos and
errors.
With each account, an electronic mail address (this is a mandatory
attribute for all guarded objects) will be used by the NCC and data-
base software. To make this flexible for the guardian a ".forward"
file with the account which can be change when required. This will
mean mail sent to <guardian-name(a)guardian.ripe.net> will go the to
correct guardian.
3.2. How does it work ?
For each of the guarded files found on `guardian.ripe.net' the data-
base software will load any guarded attribute value(s) for the net-
work object(s) listed in the guarded file. This will take place at
the same time as the database is garbage collected (currently at
0500 MET). If a conflict is found (i.e if more than one entry exists
for an attribute which can only contain one entry, currently only
"aut-sys" contains this property), the current value will remain
unchanged and all guardians involved in the conflict will be sent an
electronic mail message informing them of the conflict. See Appendix
B for an example.
If no conflict is found the attribute will be updated with the
guarded value.
Correspondingly, to remove a guarded attribute just remove the net-
work entry from the relevant guarded file and it will be deleted at
the next update run. To be notified of this delete the "notify"
attribute should be used.
If a guardian file contains an entry which is not in the database
then the guardian will be notified as part of the conflict handling
procedure.
If an update is sent to the database software using another mechan-
ism (i.e. mail to auto-dbm(a)ripe.net) that contains a guarded attri-
bute, this will not be allowed to change the guarded attribute. If
the value of the attribute is the same as what is currently
registered in the database then no warnings will be given. However,
if the update contains a value for a guarded attribute that is dif-
ferent to that registered in the database, a warning will be sent to
the originator and the guarded value will remain unchanged. Any
changes of other (unguarded) fields in the update will be checked
for syntactic correctness and if they pass will go through to the
database irrespective of any conflicts for the guarded fields.
When through the normal database update procedure an object with
guarded attributes is deleted, the guardians of these guarded attri-
butes will be notified of this deletion. Only deletions will be
notified in this way to guardians. For normal changes the "notify"
attribute of the database should be used.
ripe-???.txt 11th July, 1994
- 5 -
Although the guarded process will run once a day as part of the
database garbage collection procedure it will also be possible to,
"on request to the NCC", run an emergency guarded update process for
a particular guarded object.
To have complete guardian accounts removed from the NCC machine, and
thus all references to this guarded value, please contact the RIPE
NCC at <ripe-dbm(a)ripe.net>. Removing an account and the guardian
file that goes with it means that this guarded value will not be
added any longer to any of the objects in the database.
4. Block Splitting
4.1. Current implementation
Whilst it was not directly stated in ripe-108. The implementation
used for guarded attributes meant that if a value in a guardian file
matched any value which was part of an object registered as a range
in the database the object would be automatically split into
separate objects by the guarded field mechanism. For example, if we
had a database registered object of the following:
inetnum: 193.0.0.0 - 193.0.3.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
And we entered in the AS3333 file the entry 193.0.1.0, the guarded
field mechanism would produce the following entries:
inetnum: 193.0.0.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
ripe-???.txt 11th July, 1994
- 6 -
inetnum: 193.0.1.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
aut-sys: AS3333
changed: tony(a)ripe.net 930312
source: RIPE
inetnum: 193.0.2.0 - 193.0.3.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
Here you can see the original object (193.0.0.0 - 193.0.0.0) has
been split into three objects with the 193.0.1.0 object having the
associated aut-sys attribute value AS3333 added.
4.2. A change in implementation - exact match algorithm
Due to implementation restrictions the current automatic splitting
technique will not be used anymore. A guarded attribute will now
only be updated (in accordance with the details in 3.2) if the
object value and the value in the guarded file are EXACTLY the same.
If they DO NOT match the guardian will be notified that the entry in
the guarded file could not be found in the database.
One direct implication of this is that the guardian must now know
the exact value of the object registered in database before he or
she can update the object with their guarded attribute value. This
will mean that some manual block splitting may need to take place
before the attribute can be successfully added. This is an extremely
simple procedure. This produce can be summarised as the following
simple steps:
1) Delete the current object
2) Send in new objects split at correct values to provide exact
match needed for adding relevant guarded attributes.
ripe-???.txt 11th July, 1994
- 7 -
If we look at the above example of an object registered as 193.0.0.0
- 193.0.3.0 in the database and we would like to add the guarded
aut-sys attribute to 193.0.1.0. We would need to send the following
message to auto-dbm(a)ripe.net:
inetnum: 193.0.0.0 - 193.0.3.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
delete: tony(a)ripe.net deleted for guarded split
inetnum: 193.0.0.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
inetnum: 193.0.1.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
ripe-???.txt 11th July, 1994
- 8 -
inetnum: 193.0.2.0 - 193.0.3.0
netname: NCC-RS-TEST
descr: Test networks
country: NL
admin-c: Tony Bates
tech-c: Tony Bates
tech-c: Marten Terpstra
connect: RIPE
changed: tony(a)ripe.net 930312
source: RIPE
The key point to note is the ordering of the update sent to auto-
dbm(a)ripe.net. The delete of the original entry must take place
first. The split objects can then be added without any problems.
The objects can of course be sent in separate messages if preferred.
5. Conclusion
The update procedure as detailed above has the following advantages:
o Authorisation of adding/deleting is guaranteed.
o No need for mailing back and forth of authorisation messages.
o Simple procedure for both database maintainers and guardians.
o Guardians keep full control of their attribute.
It allows for the addition of any number of guarded attributes in
the future. It describes a simple but effective procedure for main-
taining the guarded files whilst not precluding alternate mechanisms
in the future.
6. References
[1] Bates, T., Jouanigot, J-M., Karrenberg, D., Lothberg, P.,
Terpstra, M., "Representation of IP Routing Policies in the
RIPE Database", RIPE-81, February 1993.
[2] Bates, T., Karrenberg, D., "Description of Inter-AS Networks in
the RIPE Routing Registry", RIPE-103, December 1993.
[3] Karrenberg, D., "RIPE Database Template for Networks", RIPE-50,
April 1992.
[4] J.-M. Jouanigot, "Policy based routing within RIPE", May 1992.
[5] Bates, T, "Support of Guarded fields within the RIPE Database",
July 1994.
ripe-???.txt 11th July, 1994
- 9 -
Appendix A - Format of Guardian Files.
We propose to keep the file format as simple as possible. The name
of the file is identical to the name of guarded object. The format
used within the file is kept simple. It allows lines to be either
comments or the actual object entry that is to be guarded. A comment
must contain either a semi-colon (;) or hash (#) at the beginning of
the comment line. The object name entries must be exactly the same
as they are in the database. Currently, the only object containing
guarded attributes is the "inetnum" object so the file can contain
either the `well-known' dotted quad network notation or RIPE dotted
quad range notation. Here is a simple example of what the AS1104
guarded file would look like. The file would be stored in the home
directory of the AS1104 account on guardian.ripe.net and be called
AS1104 (told you it was simple). It would contain something like the
following:
#
# File : AS1104
#
; An alternate comment format
;
; This file was updated by jan.dijkstra(a)gouda.nl
; on 940109
;
192.16.183.0
192.16.185.0 - 192.16.186.0
192.16.194.0
192.16.199.0
192.87.45.0
Empty lines in the file are also ignored but you are encouraged to
keep the file as concise as possible.
As stated above, a tool known as `checkguard' will be available to
make it simple to check the syntax of the guarded file.
NOTE: the entry in the file must match exactly the object entry in
the database. See section 4 for more details.
ripe-???.txt 11th July, 1994
- 10 -
Appendix B - Example of conflict handling
If a conflict occurs (e.g. by listing the same network number in
more than one AS guarded file), then each of the guardians involved
will be notified of the conflict by electronic mail. Let's look at a
simple example. Suppose the guardians for AS1104 and AS2122 update
their relevant guardian files and create a conflict by having the
same network in them. For this example he network in question is
"192.16.183.0". Here is the AS1104 guardian file:
#
192.16.183.0
192.16.185.0
192.16.186.0
192.16.194.0
192.16.199.0
192.87.45.0
And here is the AS2122 guardian file:
#
192.16.183.0
193.0.0.0 - 193.0.7.0
As you can see "192.16.183.0 exists in both files.
At update time the following mails are generated. Firstly, to the
guardian of AS2122.
Date: Fri, 14 Jan 1994 13:22:43 +0100
Message-Id: <9401141222.AA07125(a)ns.ripe.net>
From: RIPE Database Conflict Handler <ripe-dbm(a)ripe.net>
Subject: Guarded attributes conflicts found
To: as2122(a)ripe.net
Dear Guardian,
One or more conflicts have been found regarding guarded
attributes in the RIPE database. Some of the conflicts
concern the guarded values you are a guardian for.
Please verify and correct the conflicts below.
The guarded values for objects below have been set to
the value they had in the database before this guarded
attributes run.
Kind Regards,
RIPE Database Conflict Department
------
"192.16.183.0" also appears in guardian files: AS1104
And similarly to the AS1104 guardian.
ripe-???.txt 11th July, 1994
- 11 -
Date: Fri, 14 Jan 1994 13:22:42 +0100
Message-Id: <9401141222.AA07121(a)ns.ripe.net>
From: RIPE Database Conflict Handler <ripe-dbm(a)ripe.net>
Subject: Guarded attributes conflicts found
To: as1104(a)ripe.net
Dear Guardian,
One or more conflicts have been found regarding guarded
attributes in the RIPE database. Some of the conflicts
concern the guarded values you are a guardian for.
Please verify and correct the conflicts below.
The guarded values for objects below have been set to
the value they had in the database before this guarded
attributes run.
Kind Regards,
RIPE Database Conflict Department
------
"192.16.183.0" also appears in guardian files: AS2122
>From this you can see conflict can be quickly and easily resolved,
assuming good collaboration between the guardians. The existing
database entry will of course not be changed with regard to the
guarded attribute) as long as there exists a conflict.
ripe-???.txt 11th July, 1994
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