From: Victor Cappuccio (vcappuccio@desca.com)
Date: Sat Dec 23 2006 - 16:58:58 ART
Hehe please dismiss my post, I read wrong I thought that in between R2
and R4 you had an ospf adjacency
Nice Question for Gurus In the list
Thanks!
Victor.-
R4#show ip bgp 10.10.10.0
BGP routing table entry for 10.10.10.0/24, version 0
Paths: (1 available, no best path)
Not advertised to any peer
Local
10.10.10.10 (metric 11) from 1.1.1.1 (100.100.100.100)
Origin IGP, metric 0, localpref 100, valid, internal, not
synchronized
Originator: 10.10.10.10, Cluster list: 100.100.100.100
R4#show ip route 10.10.10.10
Routing entry for 10.10.10.0/24
Known via "ospf 1", distance 110, metric 11, type intra area
Last update from 192.168.14.10 on Ethernet0, 00:00:49 ago
Routing Descriptor Blocks:
* 192.168.14.10, from 9.9.9.9, 00:00:49 ago, via Ethernet0
Route metric is 11, traffic share count is 1
-----Original Message-----
From: Victor Cappuccio
Sent: Saturday, December 23, 2006 2:39 PM
To: 'haducbinh'; swm@emanon.com; ccielab@groupstudy.com
Subject: RE: BGP Synchronization
Hi, by chance do you have a rib failure in R4?
http://www.cisco.com/warp/public/459/bgpfaq_5816.shtml#twenty-three
please can you send a show ip bgp
Victor.-
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
haducbinh
Sent: Saturday, December 23, 2006 4:27 AM
To: swm@emanon.com; ccielab@groupstudy.com
Subject: RE: BGP Synchronization
Thanks Scott!
But I don't understand how to resolve follow problem:
This is topology: R1------R2----R3----R4-----R5
IGP information:
R2,R3,R4: running OSPF
BGP information:
R1 in AS 1000
R5 in AS 5000
R2,R3,R4 in AS 100, must enable synchronyzation all router and R3 is
route-reflector of R2, R4
The problem is: R1 advertise network "X" to R2 via BGP, then R2
redistribute
network "X" to OSPF because of BGP synchronyzation rule, and at R4
received
2 route "X": one via OSPF(with router-id R2) and one via BGP(with
router-id
R3). Because of this, route "X" unsyn. So R4 DO NOT advertise route "X"
to
R5!
I can not find solution to this situation! Can not change bgp router-id
on
R3 equal with ospf router-id on R2 (if we do that, route "X" via BGP on
R3
will unsyn).
HaDucBinh
Email: haducbinh@vnpro.org
Y/M: haducbinh
Phone: +84 908 191 322
------------------------------------------------------------------------
--- Vietnamese Professionals (VnPro) Cisco Authorised Training 149/1D Ung Van Khiem St - Ward 25 - Binh Thanh Dist - HCMC Tel: (08) 5124257 - (08) 5125314 Fax: (08) 5124314 Website: http://vnpro.vn Support Forum: http://vnpro.org-----Original Message----- From: Scott Morris [mailto:swm@emanon.com] Sent: Saturday, December 23, 2006 9:50 AM To: 'haducbinh'; ccielab@groupstudy.com Subject: RE: BGP Synchronization
Yup, it's right. Says so in the RFC.
I think RFC1403 was the first to lay this out...
"GP Identifier and OSPF router ID
The BGP identifier MUST be the same as the OSPF router id at all times that the router is up.
This characteristic is required for two reasons.
i Synchronisation between OSPF and BGP
Consider the scenario in which 3 ASBRs, RT1, RT2, and RT3, belong to the same autonomous system.
+-----+ | RT3 | +-----+ |
Autonomous System running OSPF
/ \ +-----+ +-----+ | RT1 | | RT2 | +-----+ +-----+
Both RT1 and RT2 have routes to an external network X and import it into the OSPF routing domain. RT3 is advertising the route to network X to other external BGP speakers. RT3
must use the OSPF router ID to determine whether it is using RT1 or RT2 to forward packets to network X and hence build the correct AS_PATH to advertise to other external speakers.
More precisely, RT3 must determine which ASBR it is using to reach network X by matching the OSPF router ID for its route to network X with the BGP Identifier of one of the ASBRs, and use the corresponding route for further advertisement to external BGP peers.
ii It will be convenient for the network administrator looking at an ASBR to correlate different BGP and OSPF routes based on the identifier."
HTH,
Scott
-----Original Message----- From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of haducbinh Sent: Friday, December 22, 2006 2:56 AM To: ccielab@groupstudy.com Subject: BGP Synchronization
Hi GS!
Just want to make sure about BGP synchronization work. we have 2 rules
The first:
IBGP learned prefix must have corresponding prefix listed in local forwarding table if that IBGP prefix is to be advertised to another BGP speaker.
The second:
The RID of OSPF(ASBR) and RID of advertising IBGP speaker must match when OSPF is underlying IGP.
The first rule I know how it work!
But the second rule, is it right?
If so, in this case, we have to change RID of IBGP speaker to match with RID of OSPF router?
Thanks!
HaDucBinh Email: <mailto:haducbinh@vnpro.org> haducbinh@vnpro.org Y/M: haducbinh Phone: +84 908 191 322 ------------------------------------------------------------------------ --- Vietnamese Professionals (VnPro) Cisco Authorised Training 149/1D Ung Van Khiem St - Ward 25 - Binh Thanh Dist - HCMC Tel: (08) 5124257 - (08) 5125314 Fax: (08) 5124314 Website: <http://vnpro.vn> http://vnpro.vn Support Forum: <http://vnpro.org> http://vnpro.org
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