From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Sun May 14 2006 - 23:06:10 ART
The OSPF RID needs to be unique. Try it out for yourself and see what
happens.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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________________________________
From: CCIEin2006 [mailto:ciscocciein2006@gmail.com]
Sent: Sunday, May 14, 2006 9:09 AM
To: Brian McGahan
Cc: ccielab@groupstudy.com
Subject: Re: BGP Synchronization - When do OSPF and BGP router ID need
to match?
Excellent - this was just the answer I was looking for.
Thanks Brian.
As far as setting R2's OSPF RID to be the same as R1's BGP RID, would R1
and R2 even establish adjacency if they had the same OSPF RID?
On 5/14/06, Brian McGahan <bmcgahan@internetworkexpert.com> wrote:
The answer is... it depends. The synchronization rules states that for
every iBGP learned route you must have a matching IGP route, and if that
IGP is OSPF the BGP RID and the OSPF RID must match. Suppose that R1's
RID for both BGP and OSPF is 1.1.1.1 and R2's is 2.2.2.2. In that
circumstance the OSPF RID R3 sees will be 2.2.2.2 (the originator of the
LSA) and the BGP RID it sees will be 1.1.1.1 (the reflector of the BGP
route). In this case the route will not be considered for bestpath
selection. In this case you can trick R3 into accepting the route if
you set R2's OSPF RID to be the same as R1's BGP RID. The easier
solutions however would be to disable synchronization on R1 and R3, to
peer R2 and R3 via iBGP, or to run confederation inside the AS
(synchronization only applies to iBGP learned routes).
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
24/7 Support: http://forum.internetworkexpert.com
Live Chat: http://www.internetworkexpert.com/chat/
________________________________
From: nobody@groupstudy.com on behalf of CCIEin2006
Sent: Sat 5/13/2006 1:43 PM
To: ccielab@groupstudy.com
Subject: BGP Synchronization - When do OSPF and BGP router ID need to
match?
Hello group,
Please examine the following setup:
10.1.1.0
|
(R2)
|
BGP
|
(R1)---BGP---(R3)
All three routers are running ospf and iBGP with Synchronization
enabled.
R1 is acting as route reflector for R2 and R3.
Will the 10.1.1.0 network advertised by R2 appear in the BGP table of
R3?
If not please explain why.
This archive was generated by hypermail 2.1.4 : Thu Jun 01 2006 - 06:33:21 ART