Summary

  • Simon Sohel Baroi and Aftab Siddiqui coauthored APNIC prop-154, which replaced the old /23 starting size for an IXP's IPv4 peering LAN with a /26 default.
  • The enacted rule connects larger blocks to projected peer counts or existing use, and requires a replaced block back within three months.

Sixty-four seats at the first table

The first IXP address block used to resemble a banquet booking for 512 guests, even when only a small group had arrived. Baroi and Siddiqui asked APNIC to change the reservation. Their prop-154 record names both authors and states the move from a /23 default to /26. A /26 contains 64 addresses. The numbers are small enough to fit on a napkin; the operating consequences reach the peering LAN, where exchange participants connect their routers.

APNIC's published policy, section 6.2.4, now starts a new IXP at /26. It offers up to /25 when the exchange can demonstrate more than 60 peers on that LAN within 12 months, and up to /23 or its current highest delegation when it can demonstrate more than 100. Once 60% of a smaller-than-/24 delegation is used, the holder can request up to /23. The existing block must be returned within three months of the replacement. A large exchange already holding the old maximum /23 can seek a contiguous /22, if available, at 60% use, with the same return clock. The policy sets /22 as the overall maximum.

That return clock is the sting in the sensible sizing. An exchange can grow; its operators may then need to renumber the peering LAN while keeping members connected. The APNIC text sets the obligation and deadline. It supplies no measured bill for the change. A smaller first grant conserves address space on paper, while the replacement mechanism asks an operator to plan growth and migration as one job.

The policy also keeps the address block in its lane. IXP IPv4 under this section is for peering, is non-transferable and cannot be announced in the global routing table, apart from mistakes. The constraint helps explain why a block allocated to a shared peering fabric is treated differently from address space sought for a routed network.

A vote, then a rule

Version 1 appeared in August 2023 and version 2 in September. APNIC 56 sent the proposal back for discussion; APNIC 57 reached consensus in March 2024. The Executive Council endorsed it that June, and the text became APNIC-127-v015 in February 2025. The proposal page still displays an impact assessment of version 1. Its older 80% figure is an interesting fossil; the active section says 60%. For the operator ordering addresses today, the published policy wins.

Original records