AS Number Change Could Affect Internet Routing Beginning January 1st 2009
Regional Internet Registries (RIRs), including the RIPE NCC (Network Coordination Centre), have warned that routers and network management software should be upgraded ahead of the increased distribution of four-byte (also known as 32-bit) Autonomous System (AS) numbers.More here.
AS numbers are a vital part of the Internet’s core routing system, the Border Gateway Protocol (BGP). With existing two-byte AS numbers predicted to run out in early 2011, RIRs will issue four-byte AS numbers by default (unless otherwise specifically requested) beginning 1 January 2009, as the next phase of a transition from two- to four-byte numbers. Following a globally coordinated policy, RIRs began allocating four-byte AS numbers by request only in January 2007; January 2009 marks the transition to allocating four-byte AS numbers by default...
Without timely support from vendors, network operators risk having routers and network administration systems that won’t accept the expanded four-byte number format. As such, the RIRs urge operators to verify their vendors’ routers will support four-byte AS numbers.
Additional resource: RIPE NCC: ASN32 (32-bit, or 4-byte, ASN) FAQ. -ferg