as path filtering -- cisco implementation

James haesu at towardex.com
Fri Jul 16 18:47:16 UTC 2004


> Is inbound as-path filtering an efficient way of
> preventing routes from entering your bgp table? How
> come the filtered routes still show up in the bgp
> table and not in the routing table? What is hit on the
> CPU? 

AFAIK, it shouldn't show up on bgp table if you are filtering inbound to you.
Do a sh ip bgp a.b.c.d/affectedaddr please.

Remember that Cisco's bgp implementation is scan-based, so it takes a bit of
time for policy changes to kick in. Try doing 'clear ip bgp w.x.y.z in' in an
attempt to speed it up.

-J

-- 
James Jun                                            TowardEX Technologies, Inc.
Technical Lead                        Network Design, Consulting, IT Outsourcing
james at towardex.com                  Boston-based Colocation & Bandwidth Services
cell: 1(978)-394-2867           web: http://www.towardex.com , noc: www.twdx.net



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