32-bit ASes at routeviews

Iljitsch van Beijnum iljitsch at muada.com
Sun Dec 16 22:48:13 UTC 2012


Looking for 32-bit AS numbers, I get some strange results from routeviews:

route-views>sh ip bgp regexp _23456_
BGP table version is 2393809200, local router ID is 128.223.51.103
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*  31.177.16.0/22   128.223.253.10                         0 3582 3701 3356 23456 3.1043 i
*  46.29.72.0/21    129.250.0.11           285             0 2914 12389 12389 12389 12389 23456 3.627 i
*  46.243.96.0/21   154.11.11.113            0             0 852 174 39704 39704 23456 3.787 i
*  91.208.62.0/24   154.11.11.113            0             0 852 174 39704 39704 23456 3.787 i
*  91.217.87.0/24   194.85.40.15                           0 3267 174 23456 3.661 i
*  91.230.169.0/24  208.51.134.254       13905             0 3549 29152 29152 29152 29152 23456 23456 23456 23456 3.1426 i
*  91.238.8.0/24    194.85.40.15                           0 3267 8220 23456 3.2040 i
*  111.235.148.0/22 194.85.40.15                           0 3267 9498 9730 23456 i
*  141.0.176.0/21   129.250.0.11           285             0 2914 12389 12389 12389 12389 23456 3.627 i

Unless I missed something, AS 23456 is supposed to show up as a stand-in for 32-bit ASNs on 16-bit BGP implementations, not in _addition_ to 32-bit ASNs. So the penultimate line would make sense if the other lines weren't there and the others don't make sense period.

Maybe a bug in the IOS they're running?

route-views>sh ver
Cisco IOS Software, 7200 Software (C7200P-ADVENTERPRISEK9-M), Version 12.4(24)T2, RELEASE SOFTWARE (fc2)

Or is something else going on?


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