From: Mike Tancsa

Hi, In my case, I have 6453 and 174 for transit. I want to get to 577 which is directly connected to 6453 and 174. 577 has a higher local pref on paths via 174. Short of shutting my 174 session (or some deaggregation), I dont have a way to influence how 577 gets back to me. I can easily exit out 6453, but it does nothing for the return packets. I have enough capacity on 6453 to handle all my traffic, but its a Draconian step to take and some traffic via 174 is fine and would be worse if I fully shut the session. (ie. peers of 174 in Toronto)

That's because Cogent has chosen to not give us the BGP communities needed to influence traffic destined to you from their other peers. They're one of the providers I use and I just turn them off when they are having issues. With Level 3, for example, I can path prepend to just certain remote AS's, etc., it's nice to have that control. Dave