From: CCIEin2006 (ciscocciein2006@gmail.com)
Date: Sun May 14 2006 - 11:09:09 ART
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
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>
> ________________________________
>
> 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.
>
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