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Selecting which /8 to allocate to an RIR

9 September 2009
By Leo Vegoda

I’ve previously written about the problem with IPv4 /8s which have been used to number IP networks in an unofficial and improper way.

The problem is that the unofficial usage makes it more difficult for ISPs to bring these addresses into use when they are officially allocated and so less desirable. But we have to allocate IPv4 addresses to the RIRs as long as we still have them and they still request them. We just need to implement a mechanism to select which /8 is allocated to which RIR.

The mechanism we have implemented reserves two of the /8s showing the least unofficial use for each of the newest RIRs. AfriNIC and LACNIC have fewest IPv4 /8s and service the regions with the most developing economies. We decided that those RIRs should have four of the easiest to use /8s reserved for them.

The other /8s are split between two pools and when APNIC, ARIN or the RIPE NCC qualify for additional IPv4 address space they will be allocated one /8 from each pool, with the /8 being chosen using a verifiable random selection mechanism. The mechanism is based on the “Publicly Verifiable Nomcom Random Selection” mechanism described in RFC 2777.

The sources of randomness used are the prices of the FTSE 100, Dow Jones Industrial Average and Hang Seng Index from midday at the exchange site the day after the request is received, as published on the Yahoo! Finance web site.

The pool of /8s which have been used to number IP networks in an unofficial and improper way is larger than the other pool. So when the smaller pool runs out, all allocations to APNIC, ARIN and the RIPE NCC will come from the larger pool until it too is empty. Then, if any of the /8s reserved for AfriNIC and LACNIC have not been allocated they will become part of a single pool used for all RIRs.

Of course, when all of this is done, there are still five /8s set aside for the implementation of the Global Policy for the Allocation of the Remaining IPv4 Address Space. Very little use of those /8s was detected in our 2008 research.


Leo Vegoda