AT&T routing issue

Tue Nov 4 23:20:36 UTC 2008

Hi all,

We have recently brought up some BGP sessions with a new provider, and
have found that we can get end to end connectivity through the new
provider to pretty much everywhere except networks behind AT&T (AS7018).

We are able to see our routes in AT&T's route server, but all
traceroutes from our network to hosts behind 7018 stop at AT&T's border.
We are multihomed, so I've local-prefed up our secondary ISP and the
problem resolves immediately.

Our upstream (AS9443) and their upstream (AS11867) have been chasing
this up with AT&T for a couple of days, but don't seem to have had made
much progress.

Does anyone have any suggestions as to what could be causing this, or a
contact at AT&T who might be able to assist?

Thanks,

Alex