On Sep 23, 2015, at 5:38 PM, Jason Bullen <jmbullen21@gmail.com> wrote:
I've always worked in enterprise only so I thought you guys might be able to help me with this one. We are dual homed to Verizon and AT&T. We prepend all our prefixes out AT&T to make them least preferred. During a recent issue we found some users were coming in via AT&T. Using various looking glasses it looks like if I use an AT&T server(route-server.ip.att.net) the best path is the prepended route through AT&T; in fact,I don't even see the VZB route. If I use a 3rd party looking glass(router-server.he.net) I see what I anticipated, which is the shorter AS-Path through VZB.
So if my research is correct, the internet prefers Verizon UNLESS they are a direct AT&T customer then they would use the AT&T circuit. Is this a standard practice that I should assume to encounter?
Yes.