From: Carlos G Mendioroz (tron@xxxxxxxxxxx)
Date: Tue Jun 25 2002 - 08:07:02 GMT-3
In a nutshell, iBGP sync when the IGP is OSPF requires not only that
the received route is already in the FIB (routing table) but also
that the OSPF originator's ID is the same as the iBGP neighbour's ID.
This creates problems especially with route reflectors, but also
when OSPF crosses AS borthers like in confeds.
Hunt Lee wrote:
>
> Okay folks, I'm back as I have bummed into another problem last nite
> =)
>
> 150.150.150.0/24---RTA ---RTB ---RTD---RTF
> | |
> RTC RTE
>
> RTA, B, C, D, & E are in a Confederation called AS 1, in which:-
>
> RTA is sub-AS 65530
> RTB & RTC are both in sub-AS 65531
> RTD & RTE are both in sub-AS 65532
>
> RTF is in AS 2
>
> RTB, C, D & E are running OSPF as IGP. And OSPF is being
> redistributed into BGP at RTB.
>
> The network i172.16.0.12/30 is being advertised into BGP by BGP
> "network" command on RTD. i172.16.0.13 & .14 are the interfaces IP
> for RTD & RTE.
>
> Ok, here is the thing. RTC just can't see this link via BGP (it kept
> on saying it's not sync), even though it is reachable via OSPF. With
> OSPF, shouldn't BGP think that it is sync, and installs it as best
> route?
>
> Am I missing something here?
>
> RouterC#sh ip bgp
> BGP table version is 8, local router ID is 172.16.0.2
> 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
> * i150.150.150.0/24 193.16.0.2 0 100 0 (65530) i
> *>i172.16.0.0/30 172.16.0.1 0 100 0 ?
> * i172.16.0.12/30 172.16.0.18 30 100 0 ?
> *>i172.16.0.16/30 172.16.0.1 0 100 0 ?
> *>i193.16.0.0/30 172.16.0.1 0 100 0 ?
> * i193.16.0.8/30 172.16.0.18 0 100 0 (65532) i
>
> RouterC#sh ip bgp 172.16.0.12/30
> BGP routing table entry for 172.16.0.12/30, version 0
> Paths: (1 available, no best path)
> Not advertised to any peer
> Local
> 172.16.0.18 (metric 128) from 172.16.0.1 (193.16.0.1)
> Origin incomplete, metric 30, localpref 100, valid, internal,
> not synchronized, ref 2
>
> RouterC#sh ip route
> 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, L1 - IS-IS level-1, L2 - IS-IS level-2, * -
> candidate default U - per-user static route, o - ODR
>
> Gateway of last resort is not set
>
> 172.16.0.0/30 is subnetted, 3 subnets
> O 172.16.0.16 [110/128] via 172.16.0.1, 01:43:32, Serial1
> O 172.16.0.12 [110/192] via 172.16.0.1, 01:43:32, Serial1 <--
> but it is reachable via OSPF ??
> C 172.16.0.0 is directly connected, Serial1
> 193.16.0.0/30 is subnetted, 1 subnets
> O 193.16.0.0 [110/74] via 172.16.0.1, 01:43:32, Serial1
> RouterC#
>
> Thanks all!
>
> H.
>
> http://www.sold.com.au - SOLD.com.au
> - Find yourself a bargain!
This archive was generated by hypermail 2.1.4 : Tue Jul 02 2002 - 08:12:41 GMT-3