From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Mon May 15 2006 - 13:24:01 ART
You would have to turn synchronization off on R1 for this to work,
because R2 is its iBGP neighbor. If R1 and R2 were in different ASs
this would also work. The problem with this workaround is that it only
works on one single neighbor :)
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: Victor Cappuccio [mailto:cvictor@protokolgroup.com]
> Sent: Sunday, May 14, 2006 10:18 PM
> To: Brian McGahan
> Cc: ccielab@groupstudy.com
> Subject: RE: BGP Synchronization - When do OSPF and BGP router ID need
to
> match?
>
> Hi Brain, many thanks for your contribution to this list as always
>
> Answering your question:
>
> If you have the same Router ID this happens:
> *May 14 20:55:21.632: %OSPF-4-DUP_RTRID_NBR: OSPF detected duplicate
> router-id 10.2.2.2 from 204.12.1.2 on interface FastEth0
>
> But I got interested in one point you mentioned, I love SRT...
>
> "R3 into accepting the route if you set R2's OSPF RID to be the same
as
> R1's
> BGP RID."
>
> please what I'm doing wrong?
>
> Having this situation
>
> 10.1.1.0
> |
> (R2)
> |
> BGP
> |
> (R1)---BGP---(R3)
>
>
> So I did that:
>
>
> R2#show ip ospf
> Routing Process "ospf 1" with ID 10.2.2.2
>
> R1#show run | be router bgp
> router bgp 100
> synchronization
> bgp router-id 10.2.2.2
>
>
> R1#show ip bgp summ
>
> BGP router identifier 10.2.2.2, local AS number 100
>
> BGP table version is 1, main routing table version 1
>
> 42 network entries using 4914 bytes of memory
>
> 42 path entries using 2184 bytes of memory
>
> 7/0 BGP path/bestpath attribute entries using 868 bytes of memory
>
> 2 BGP AS-PATH entries using 48 bytes of memory
>
> 1 BGP community entries using 24 bytes of memory
>
> 0 BGP route-map cache entries using 0 bytes of memory
>
> 0 BGP filter-list cache entries using 0 bytes of memory
>
> BGP using 8038 total bytes of memory
>
> BGP activity 176/134 prefixes, 296/254 paths, scan interval 60 secs
>
>
>
> Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down
> State/PfxRcd
> 10.1.1.1 4 100 4564 2308 1 0 0 00:13:39
> 2
>
> 10.6.6.6 4 100 83 66 1 0 0 00:24:46
> 40
>
>
> BUT:
>
> R3#show ip bgp
> BGP table version is 101, local router ID is 10.1.1.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
in
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 10.0.0.0 0.0.0.0 0 32768 i
> *> 163.1.0.0 0.0.0.0 0 32768 ?
> R3#
>
> What I'm doing wrong here :S
>
> R1#show run | be router bgp 100
> router bgp 100
> synchronization
> bgp router-id 10.2.2.2
> bgp log-neighbor-changes
> neighbor 10.1.1.1 remote-as 100
> neighbor 10.1.1.1 update-source Loopback0
> neighbor 10.1.1.1 route-reflector-client
> neighbor 10.1.1.1 next-hop-self
> neighbor 10.1.1.1 send-community
> neighbor 10.6.6.6 remote-as 100
> neighbor 10.6.6.6 update-source Loopback0
> neighbor 10.6.6.6 route-reflector-client
> neighbor 10.6.6.6 next-hop-self
> neighbor 10.6.6.6 send-community
> no auto-summary
>
> Thanks
> Victor.
>
>
>
>
> -----Mensaje original-----
> De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de
> Brian
> McGahan
> Enviado el: Domingo, 14 de Mayo de 2006 10:06 p.m.
> Para: CCIEin2006
> CC: ccielab@groupstudy.com
> Asunto: RE: BGP Synchronization - When do OSPF and BGP router ID need
to
> match?
>
> 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.
> http://www.InternetworkExpert.com <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
> <http://forum.internetworkexpert.com/>
> Live Chat: http://www.internetworkexpert.com/chat/
>
> ________________________________
>
> 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