At 10:03 PM 23/12/2005, Roger Jorgensen wrote:
On Fri, 25 Nov 2005, Gert Doering wrote: <snip>
The idea is that ULAs are random-generated in a way that makes it "fairly unlikely" that you end up in an address collision. But there is no guarantee, of course.
indeed. The chances of collision exceed 0.5 once the pool of random;y drawn numbers exceeds 1.24 million.
There is also a second sort of ULAs that are globally unique but still private, but as far as I know, there is no registry yet that will hand them out. So these can't be used yet.
Who would know more about this? I'm in the process of writing down some startup thoughts about how we can (and maybe should) implement IPv6 here where I work. It's a closed national network where security is prio 1 and we might also have to work/connect to other network of the same type in other countries... in short, we need to be globaly unique so we actually need that registrary to be there:)
the original ULA document combined both self-selected ULAs and registry-selected ULAs. Over the period of a year of IETF consideration they were split in two, and the random self-selction method became RFC 4193 and the so-called centrally assigned IDs draft expired . Some URLS: - the history of the drafts: http://smakd.potaroo.net/ietf/idref/draft-ietf-ipv6-unique-local-addr/index.... - the centrally assigned drafts: http://smakd.potaroo.net/ietf/idref/draft-ietf-ipv6-ula-central/index.html There was a long discussion on the IPv6 list about the issues with the operation of a registry. I've forgotten when, but around May - July 2003 sounds familiar for some reason. The concept of a central register of unique 40bit sequences is not completely dead. At RIPE 51 I described some current work at APNIC that includes a certificate identity scheme that uses this same concept (http://www.ripe.net/ripe/meetings/ripe-51/presentations/pdf/ripe51-address-c... (see page 14 of the presentation). I also did some maths of the collision probability of random 40bit long numbers (the so-called "birthday problem" in an expired draft (http://smakd.potaroo.net/ietf/idref/draft-huston-ipv6-local-use-comments/ind...). It _may_ be the case that a form of centrally assigned unique 40 bit strings for use in the context of the original model of centrally-assigned unique local addresses may be a useful by-product of the certification work - but if it proceeds that this is likely to be some time away yet from becoming part of the service portfolio associated with certification. regards, Geoff