23456 without AS4_PATH?

Sat Feb 28 13:52:30 UTC 2009

> Anyone else seeing this:
> *> 91.196.186.0/24  62.237.167.25                          0 3292 3549 15703 43531 23456 i
> 
> http://www.ietf.org/rfc/rfc4893.txt
> 6.  Transition
>    An OLD BGP speaker MUST NOT use AS_TRANS as its Autonomous System
>    number.

Seeing it here too. On our 4-byte capable routers:

91.196.186.0/24    *[BGP/170] 1d 13:36:53, MED 0, localpref 105, from 193.75.0.204
                      AS path: 16150 15703 43531 AS_TRANS I
                      AS path: 3356 6461 15703 43531 AS_TRANS I
                      AS path: 1299 3549 15703 43531 AS_TRANS I

And on our non 4-byte capable routers it is simply shown as 23456. This
ASN should not be used to originate prefixes, agreed.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no