* christopher.morrow@mci.com (Christopher L. Morrow) [Tue 12 Oct 2004, 05:18 CEST]:
a common occurance we've seen is a customer of a customer NOT announcing , nor planning on announcing, their routes to their upstream#1 which they use ONLY for outbound traffic (cheap transit for instance, and perhaps only for some portions of their total sources) though they announce to upstreams#2-N the proper sources to gather the return traffic. These things make uRPF 'difficult'.
You could use uRPF-loose there, or the customer could do: ! route-map outbound-only permit 10 match prefix-list myprefixes set community no-export ! And bash the people who, in this age, don't have "neighbor x.y.z.a send-community" on all their BGP sessions. -- Niels (who recently had a CCIE claim that he was "not aware of a single ISP accepting communities from its peers" - well, my experience begs to differ, with his employer a rare and lonely exception to the rule)