23456 is AS_TRANS. Either your router does not support 4 byte AS or there is a bug at AS 12956 or AS 12956 is intentionally prepending 23456.
Thanks, Jakob. > > Date: Tue, 20 Jun 2017 23:12:45 +0000 > From: James Braunegg <james.braun...@micron21.com> > To: "nanog@nanog.org" <nanog@nanog.org> > Subject: Long AS Path > Message-ID: <e679487be750411a874b7376a7037aa9@EX-01.m21.local> > Content-Type: text/plain; charset="us-ascii" > > Dear All > > Just wondering if anyone else saw this yesterday afternoon ? > > Jun 20 16:57:29:E:BGP: From Peer 38.X.X.X received Long AS_PATH= AS_SEQ(2) > 174 12956 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 > 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 > 23456 23456 23456 23456 ... attribute length (567) More than configured > MAXAS-LIMIT > > Jun 20 16:15:26:E:BGP: From Peer 78.X.X.X received Long AS_PATH= AS_SEQ(2) > 5580 3257 12956 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 > 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 23456 > 23456 23456 23456 23456 ... attribute length (568) More than configured > MAXAS-LIMIT > > Someone is having fun, creating weird and wonderful long AS paths based > around AS 23456, we saw the same pattern of data from numerous upstream > providers. > > Kindest Regards, > > James Braunegg > >
