From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Tue May 16 2006 - 12:20:38 ART
> To get back to old route I need to reset the peer .
>
> Just wondering if any body has seen this behaviour.
How long did you wait? Try it again and wait a few minutes before
resetting the session.
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Arun Arumuganainar
> Sent: Tuesday, May 16, 2006 9:39 AM
> To: ccielab@groupstudy.com
> Subject: BGP Route Selection Problem
>
> I have a interesting BGP route selection problem . It would be great
if
> any
> body can explain me this .
>
> Setup description :-
> ~~~~~~~~~~~~~~
>
> 1) I have BGP Synchronisation enabled and I am redistributing my BGP
> routes
> in to IGP . Here the IGP is RIP .
> 2) I learn a same prefix learned via two sources as follows
>
> a) First route via iBGP with Local-Pref set to 500
> b) Second one via eBGP with Local pref set to 300
>
> Actually I see route A is slected by the virtue of superior local pref
> .This
> is as expected.
>
> ****************************************
> Router Traces
> ****************************************
> R4#sh ip bgp
> BGP table version is 7, local router ID is 172.16.104.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> r 172.16.107.0/24 172.16.124.3 300 0 100 700 ?
> r>i 172.16.103.1 0 500 0 100 700 ?
> ****************************************
>
> Pls Note : Routes are tagged as 'r' as the SYNC is enabled and routes
are
> also learned via IGP .
>
> Step to reproduce the problem :-
>
> I shut doen the iBGP peer using neighbor shut down command and now the
> eBGP
> routes are getting comfortably installed . as given in the router
trace .
>
> ****************************************
> Router Traces
> *************************************
> R4(config-router)#neighbor 172.16.103.1 shutdown
> R4(config-router)#do sh ip bgp
> BGP table version is 9, local router ID is 172.16.104.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 172.16.107.0/24 172.16.124.3 300 0 100 700 ?
>
> ****************************************
>
> Now I bring up the BGP Peer again . Now my expectation would be iBGP
route
> should get re-installed right ??? But to my surprise it is not getting
> installed again.
>
>
> ****************************************
> Router Traces
> *************************************
> R4(config-router)#no neighbor 172.16.103.1 shutdown
> R4(config-router)#
> *May 16 14:16:40.449: %BGP-5-ADJCHANGE: neighbor 172.16.103.1 Up
> R4(config-router)#
> R4(config-router)#do sh ip bgp
> BGP table version is 9, local router ID is 172.16.104.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> * i172.16.107.0/24 172.16.103.1 0 500 0 100 700 ?
> *> 172.16.124.3 300 0 100 700 ?
>
> ****************************************
> To get back to old route I need to reset the peer .
>
> Just wondering if any body has seen this behaviour.
>
> Thanks and Regards
> Arun
>
>
This archive was generated by hypermail 2.1.4 : Thu Jun 01 2006 - 06:33:21 ART