[nsp] weird traceroute/routing issue

From: Tito B. (titobi@yahoo.com)
Date: Tue Feb 19 2002 - 03:07:38 EST


Hi!

i'm seeing strange traceroute results in my network to some hosts
whose prefix I receive from 3 external peers.

"sh ip route x.x.x.x" and "sh ip bgp x.x.x.x" would output
same path and would traverse the path on our border router.

a sh ip bgp x.x.x.x on the border would output something like:
Paths: (5 available, best #1)
peer 1 Origin IGP, metric 50, localpref 80, valid, external, best
peer 2 Origin IGP, localpref 70, valid, internal
peer 2 (received-only)
                Origin IGP, localpref 100, valid, internal
peer 3 Origin IGP, localpref 70, valid, internal
peer 3 (received-only)
                Origin IGP, localpref 100, valid, internal

but doing the trace on an aggregation router connected to
the border, parallel paths would show up on the trace,
one through the supposedly best path, peer 1, while the other
one through peer 2. Looks like parallel paths where the alternate chose
a "received-only" bgp route with a higher LocPref setting.

tracert results on a Windows box only shows one path through
peer 2 also and not through peer 1 which is the "best" path.

I understand that routes marked with received-only have been rejected
by policy on my route-maps due to soft-reconfiguration inbound configured
on my neighbor statements but why do they show up on my traces and somehow
preferred? largely due to localpref=100? is this a bug or something?

routers are 7507 and 7513 with BGP, OSPF, PIM, dCEF on the 7507 CEF on the 7513
aggregation router on 12.0(15)S1. The 7507 is connected to the 7513 via
parallel
FE links.

thanks in advance for any help.

./tito

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