From: Bob Sinclair (bsinclair@netmasterclass.net)
Date: Thu Jan 08 2004 - 11:53:04 GMT-3
This looks like the issue of non-matching OSPF-BGP RIDs. There is a paper
that discusses this situation in the free technical library on the
netmasterclass site. You might also find discussions in the groupstudy
archives. It is very difficult to get RR to work right with sync on.
HTH,
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net
----- Original Message -----
From: <arvindyadav@comcast.net>
To: <ccielab@groupstudy.com>
Sent: Thursday, January 08, 2004 2:56 AM
Subject: BGP issue - ospf, rr and no-synchronization
> r7 is RR server and r6 and r2 are client with "synchronization". r6, r7
and
> r2 running ospf and Router-id is same on both OSPF an BGP on all the
> rotuers.
>
> r7
> / \ AS2
> AS1 / \
> r8---ebgp---r6 r2
>
> r8 advertise two routes (137.20.81.0/24 and 137.20.82.0/24) to r6 and
these
> routes are appear in r6 router table as bgp route. R7 and R2 bgp table
shows
> these routes are not-synchoronized and routing table has both route as
OSPF.
> Next hop is also reachable. I don't understand why these are not
> synchronised.
>
> BGP debug show "no best path".
>
> *Mar 16 03:10:22.310: BGP(0): nettable_walker 137.20.81.0/24 no best path
> *Mar 16 03:10:22.314: BGP(0): nettable_walker 137.20.82.0/24 no best path
> *Mar 16 03:10:22.318: BGP(0): nettable_walker 137.20.86.0/24 no best
pathip
> ro
>
>
> If I put no-synchronization under bgp everything stats wokring fine. But
> question is here if the route are there in IGP then why it not woking with
> "sync". Does synchronization behave diferently with Route-refflector or I
am
> wrong somewhere ?
>
>
> R7#sh ip os
> Routing Process "ospf 1" with ID 7.7.7.7
>
>
> R7#sh ip bgp
> BGP table version is 44, local router ID is 7.7.7.7
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *>i137.20.25.0/24 137.20.64.5 100 100 0 ?
> * i137.20.40.16/28 137.20.64.5 100 100 0 ?
> * i137.20.81.0/24 137.20.86.1 0 100 0 1 i
> * i137.20.82.0/24 137.20.86.1 0 100 0 1 i
>
> R7#sh ip bgp 137.20.81.0
> BGP routing table entry for 137.20.81.0/24, version 74
> Paths: (1 available, no best path)
> Flag: 0x208
> Not advertised to any peer
> 1, (Received from a RR-client)
> 137.20.86.1 (metric 20) from 137.20.60.1 (6.6.6.6)
> Origin IGP, metric 0, localpref 100, valid, internal, not
> synchronized
>
> R7#ping 137.20.64.5
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 137.20.64.5, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 16/16/20 ms
> R7#r
> Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS
> level-2
> ia - IS-IS inter area, * - candidate default, U - per-user static
> route
> o - ODR, P - periodic downloaded static route
>
> Gateway of last resort is not set
>
> O E2 137.20.86.0/24 [110/20] via 137.20.25.2, 00:00:33, Serial1
> O E2 137.20.81.0/24 [110/1] via 137.20.25.2, 00:00:33, Serial1
> O E2 137.20.82.0/24 [110/1] via 137.20.25.2, 00:00:33, Serial1
>
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