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?