From: OhioHondo (ohiohondo@columbus.rr.com)
Date: Mon Apr 07 2003 - 10:51:37 GMT-3
Peng
BGP Synchronization with OSPF
If you are using BGP and OSPF the router must successfully match up the BGP
learned route with the IGP learned route for a route to be synchronized.
On a given router, if that router learns a prefix via EBGP and the EBGP
route is installed in the IP routing table, any identical iBGP prefix
learned WILL NOT be synchronized!!! The OSPF (IGP) route is not in the
routing table (because the EBGP route has an admin of 20) so it can't be
synchronized with the iBGP learned route.
If you disable the EBGP peering connection and reset the BGP process on the
router an OSPF route should show up in the IP routing table. If the OSPF
router ID of the router SENDING the OSPF route matches the BGP router ID of
the iBGP peer sending the route --- you will be synchronized.
Note -- if you have 2 iBGP peers sending this route to your router, only one
of them has the possibility to synchronize. The Best Route identified by the
BGP process on your router must have come from the same OSPF router that is
the source of the OSPF update in the routing table --- that is to say that
the OSPF router ID at the source of the advertisement has to equal the BGP
router ID.
I have read that Cisco does not recommend using synchronization in a full
mesh or simulated full mesh environment. They also do not recommend using it
if your AS is not a transit AS.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Peng Zheng
Sent: Sunday, April 06, 2003 7:16 PM
To: ccielab@groupstudy.com
Subject: BGP synchronize
Hi,
Routing TCPIP V2, on top of page 189. For each of
192.168.192.0 to 192.168.199.0, Sugarbush learn them
from Stowe (EBGP) and Diamond (IBGP), I use
For Sugarbush and Diamond, I use neighbor
next-hop-self on for each other.
For IBGP learned route, they are not synchronized.
What I want to do is to synchronize them. Then I
config ospf on the link between Sugarbush and Diamond.
and redistribute bgp 200 subnet into ospf, but routes
learned from IBGP are not synchronized. But if I
shutdown the EBGP link ( for example, for Sugarbush, I
shutdown the link between Stowe and Sugarbush), those
routes are synchronized.
Does anyone know why?
Thank you for help.
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