Summary

  • Carsten Schiefner's RIPE proposal 2014-01 removed the /22 minimum allocation size, the /24 sub-allocation minimum and the size floor on PA transfers; it was accepted in July 2014 and implemented that year.
  • RIPE NCC still issued its last-/8 /22 to eligible new LIRs. The change let existing holders split, sub-allocate, transfer or, under conditions, convert smaller blocks; it left routing reachability to the networks carrying them.

A ruler left on the wrong desk

An IPv4 /22 contains 1,024 addresses. In the age of the last /8, RIPE NCC's rule gave a new local Internet registry one such block. Another sentence in its policy still declared /22 the minimum allocation size. That sentence had acquired an odd second job: it could keep an existing LIR from transferring a smaller piece of address space. A /24 floor sat on sub-allocations too. The ruler had survived the job it was made for and wandered into everyone else's paperwork.

Carsten Schiefner brought the mismatch to RIPE's Address Policy Working Group in March 2014. His proposal 2014-01 cut the size language from three places: allocations, sub-allocations and re-allocations. The final version also addressed a particular annoyance for LIRs holding infrastructure space as provider-independent assignments. RIPE NCC counted 2,066 such PI assignments smaller than /22 across 1,260 LIRs in its impact analysis. If an assignment belonged to the same legal entity as the LIR, the new text opened a route to register it as provider-aggregatable allocation space. Those counts describe possible candidates in 2014, not transactions that subsequently happened.

The proposal's small print was its best argument. Schiefner said the registry should not decide how small an operator's own sub-allocation or transfer was allowed to be merely because a leftover minimum still existed. The RIPE NCC's analysis agreed on the mechanical effect: existing allocations could be split, more-specific sub-allocations made, and PA blocks below /22 transferred. It also named the operating limit. A very small prefix might run into route filters; the RIPE NCC would not make it globally reachable by approving its registration. The address book can record a choice. Routers make a separate choice.

This distinction mattered in the policy room. A small block might fit a buyer or a downstream network better than a whole /22. Yet its route might travel badly. Schiefner's answer put the sizing decision with the LIR and the reachability test with the operator. It left RIPE NCC's one-/22 last-/8 issue rule intact. The RIPE NCC member update says the proposal received only support and was accepted in July 2014; the 2014 annual report lists it among policies implemented that year.

The registry had kept an old ruler after the furniture moved. Schiefner did not smash the desk. He put the ruler back where its measurements still meant something.

RIPE original records