From: ghias hassan (ghias.hassan@gmail.com)
Date: Mon May 15 2006 - 19:33:01 ART
hi ,
is that true only for ospf or this is to be considered with eigrp or rip
ghias.
On 5/15/06, Brian McGahan <bmcgahan@internetworkexpert.com> wrote:
>
> 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
> Toll Free: 877-224-8987 x 705
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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.
> >
> >
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> >
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