Background ---------- The advisory council of ARIN asked ARIN to consider changing the current allcation policy. The initial allocation to a new LIR/ISP should be reduced from a /19 to a /20. The reason being that this would make it easier for new ARIN customers to receive an allocation directly from ARIN rather than from their up-stream provider. According to ARIN's local allocation policy they would then need to justify the utilisation of only a /21 instead of a /20 previously allocated to them by their upstream provider. Another motivation is to improve conservation of address space by reducing the amount of unused addresses in initial allocations. The new policy would not increase the load on the global routing, because the same amount of allocations would still be given out, just one longer prefix. Before deciding on this proposal ARIN has asked the other regional registries (APNIC and RIPE NCC) to also consider this change. Considerations -------------- Based on the RIPE NCC allocation data starting in 1992 we investigated how much impact the proposed change would have on the conservation of address space. We determined how many LIRs in our service region had not used more than a /20 from their initial /19 allocation within one year. The results are as follows: Of 1410 LIRs checked 304 (22%) had assigned not more than a /20 during the first 12 months of operations. This means that 78% of the LIRs had used more than a /20 within one year. The total amount of allocated but, after one year, not yet assigned address space was equivalent to 19 /16s. Some of the LIRs which did not have assigned more than a /20 after one year have since become inactive and the address space concerned will not be assigned in the foreseeable future. However 272 of the 304 are still operational and it is likely that most of them will assign more address space in the future. Further investigations showed that about 50% of those LIRs who haven't used more than a /20 appear to be multihomed. Conclusions ----------- These results have been presented to the LIR WG at the 31. RIPE Meeting in Edinburgh. The LIR WG is the body defining local address space policy for the RIPE NCC. The LIR WG didn't feel that this is a reason to change the current allocation policy. The benefits for conservation are not significant. However, the consequences for aggregation are likely to be noticeable if 80% of LIRs require a second allocation within a year. Furthermore the LIR WG expressed concerns about the routability of longer pefixes in the light of current prefix-length dependent filtering and flap dampening policies. Under the current circumstances the LIR WG did not see a valid reason to change the current allocation policy. We ask the ARIN membership to take this into consideration and consider other ways of achieving the aims of the proposed change.