On 26-apr-2005, at 15:22, Michael.Dillon@radianz.com wrote:
Note that the current HD ratio for all IPv4 address space that isn't reserved by IANA is 90.45%.
As you see the HD Ratio propsed is much higher but would help LIR's with bigger allocations to justify their IP usage.
You are comparing apples and oranges. Or maybe you have painted all your apples with orange paint.
The proposal suggests that the HD ratio should be 0.96 It does not mention a percentage. In fact, a percentage is a kind of ratio but it is not the same kind of ratio as the HD ratio.
From RFC 3194: log(number of allocated objects) HD = ------------------------------------------ log(maximum number of allocatable objects) This ratio is defined for any number of allocatable objects greater than 1 and any number of allocated objects greater or equal than 1 and less than or equal the maximum number of allocatable objects. The ratio is usually presented as a percentage, e.g. 70%. It varies between 0 (0%), when there is just one allocation, and 1 (100%), when there is one object allocated to each available address.
The comment regarding all IP address space that is not reserved by IANA is not clear whether it is talking about an HD ratio or an allocation percentage. And the most important thing is that it does not say what is the source of the numbers that lead to the 90.45 result.
Out of the 256 /8 blocks 32 are class D (224 - 239, multicast) and E (240 - 255, reserved) and three others are also unusable: 0, 10 and 127. Of the 221 usable /8s 72 were unused as of March 2005. See http://www.iana.org/assignments/ipv4-address-space . According to the ISC Domain Survey at http://www.isc.org/ds/ 317 million IPv4 hosts had a domain name in January 2005. So that's 149 * 2^24 = 2.5 billion allocatable objects with 317 million objects allocated, or: 8.501 / 9.397 = 0.9047. (log base 10.)
HD ratio for IPv4 is intended to count the number of addresses assigned by an LIR and compare that to the number of addresses that RIPE (or another RIR) has allocated to the LIR.
No, the intent of the HD ratio is to show that we need IPv6 even though only some 9% of all usable IPv6 addresses are in use. (Throw in standard disclaimer about the host count.)
When discussing "all IPv4 address space" or "IANA reserved address space" we are talking about address attributes that are not covered by the HD ratio as we know it.
The HD ratio is just a rule of thumb that says on everage, we waste one fifth to an eighth of the address length. The fact that we're now apparently using more than 90% oof the address length while including sparsely populated pre-1993 address space shows that the HD ratio isn't all that useful, although it's main point, that there are losses at allocation boundaries, is of course very true.