32-bit AS numbers in the wild (posted 2007-04-12)

In january, Geoff Huston wrote to the NANOG list:

George Michaelson, Randy Bush and myself have successfully tested the implementation of 4Byte AS BGP on a public Internet transit. The above BGP RIB snapshot was taken at a 4Byte BGP speaker in North America, showing a transit path across AS 1221, AS 4637, AS 1239 and AS 3130 , with correct reconstruction of the originating AS at the other (4Byte AS) end.

At the time of this writing, their prefix is no longer visible in the global BGP table, but telnet to route-views.oregon-ix.net and type:

show ip bgp regexp _23456_

Until the Route Views server is upgraded to support 32-bit ASes, this will give you all the prefixes/AS paths with a 32-bit AS number in them. Currently, those are:

• 84.205.88.0/24, "RIPE-NCC-RIS 4-byte ASN testing prefix", advertised from AS 196615 aka AS 3.7
• 145.125.0.0/20, "SURFNET-TEST-NETWORK 4BYTE ASN", advertised from AS 196613 aka AS 3.5

There are now patches to make OpenBGPD 32-bit AS capable and also patches for Quagga. For more information on 32-bit ASes, have a look at an earlier article on BGPexpert.com.