BGP ISSUES....

Unanswered Question
Dec 19th, 2007

we have an issue where I can see BGP prefixes in the BGP-RIB table. The prefix is coming up as 'no best path'. The routers that are advertising the routes are reachable and sync is turned off. Why can't I see the routing in the routing table?

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macarpenter Wed, 12/19/2007 - 12:25

This seems to be an issue for any networks on the 64622 AS. All other AS's are fine...




BGP routing table entry for 10.237.0.0/16, version 10082

Paths: (2 available, no best path)

Multipath: eBGP iBGP

Flag: 0x820

Not advertised to any peer

64622, (received & used)

10.250.92.9 from 10.250.92.9 (10.254.100.92)

Origin IGP, metric 4294967295, localpref 100, valid, internal

64622, (received & used)

10.250.92.10 from 10.250.92.10 (10.254.100.192)

Origin IGP, metric 4294967295, localpref 100, valid, internal


mounir.mohamed Wed, 12/19/2007 - 12:32

This is only can happen when syn is on (which is not your case because there is no sync warning in the output) or when there already route with better AD installed in the routing table, nothing can prevent one AS from install the routes in the routing table (expect memory issues)


can we share the config, i will lab it up on my Rack for you.

Richard Burts Wed, 12/19/2007 - 12:41

Marc


You say that The routers that are advertising the routes are reachable. I am not clear whether than means that the advertised next hop is reachable or just that the router peer address is reachable. If the router is reachable but the next hop address is not reachable you would get symptoms like what you are experiencing.


Can you clarify whether the next hop address is reachable?


HTH


Rick

Danilo Dy Wed, 12/19/2007 - 18:04

Hi,


Does your BGP configured for MPLS VPN multipath load sharing? It looks like it as indicated by the following;

Multipath: eBGP iBGP

Flag: 0x820


I think you should have external route and that should be the best path.


What is your "maximum-paths eibgp" value?


Regards,

Dandy

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