From: Mahmud, Yasser (YMahmud@Solutions.UK.ATT.com)
Date: Mon Nov 25 2002 - 21:42:36 GMT-3
Brian,
Thks, I guess it means if this does crop up and I can't get another IGP
routing protocol advertising it, then even though they may give me
AS no.'s to use but because they haven't mentioned not to use confed's so I
guess it would be OK to create sub-As's (picking my own sub AS no.'s) with
confed's instead of using RR
Just found the below on bug toolkit affecting all 12.x
CSCdr89673 Bug Details
Headline Sync check fails with OSPF and RRs
Product all Model
Component bgp Duplicate of
Severity 3 Status Closed
First Found-in Version 12.1(1) All affected versions First Fixed-in
Version Version help
Release Notes
The BGP synchronization check will fail if there is not an iBGP connection
to the
origination RID. In the case of route reflectors, this can easily be the
case.
Rgds,
Yasser
-----Original Message-----
From: Brian McGahan [mailto:brian@cyscoexpert.com]
Sent: Monday, November 25, 2002 11:48 PM
To: 'Mahmud, Yasser'; 'Rich Doty'; ccielab@groupstudy.com
Subject: RE: BGP route-reflector client not installing IBGP routes
Yasser,
You've pretty much answered your own question. Of the four
solutions I have presented, you're eliminating three of them.
Synchronization is only an iBGP issue. Since inter-sub-AS communication
in a confederated AS behaves as an EBGP session, synchronization does
not apply. Therefore, if the three routers were all in their own
sub-AS's, this problem would not be an issue.
HTH
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Voice: 847.674.3392
Fax: 847.674.2625
> -----Original Message-----
> From: Mahmud, Yasser [mailto:YMahmud@Solutions.UK.ATT.com]
> Sent: Monday, November 25, 2002 5:16 PM
> To: 'Brian McGahan'; 'Rich Doty'; ccielab@groupstudy.com
> Subject: RE: BGP route-reflector client not installing IBGP routes
>
> Brian,
>
> For OSPF routes.
> They will only synchronize when the OSPF router-id and bgp router-id
> match,
> so can be fixed by making sure the router
> generating the OSPF and BGP routes have the same router-id for both
> protocols
>
> The problem is that for the routes reflected by the RR , it changes
the
> router-id of bgp routes to itself.
> However the router-id for the OSPF 'O' type routes still remains the
> router
> which generated the routes so hence you get no match
> b/w the router id of the IGP and the BGP route
>
> Could you please clarify that this means it is not fixable unless the
> below
> (as mentioned in your previous thread)??
>
> 1. fully mesh your iBGP sessions
> 2. use confederation
> 3. use another IGP besides OSPF
> 4. turn synchronization off
>
> Just wondering for lab purposes if this crops up and asked to not
create
> an
> IBGP session b/w the route-reflector clients and not to turn off
> synchronization and to redistribute the loopback routes via OSPF.
>
> Then do I in addition reditsribute routes those via another IGP if I
have
> another routing protocol running on both the routers
> (as it may not mention I can't redistribute via another routing
protocol)
> &
> if not possible what else can I do ???
>
> Thks,
> Yasser
>
>
> -----Original Message-----
> From: Brian McGahan [mailto:brian@cyscoexpert.com]
> Sent: Monday, November 25, 2002 8:52 PM
> To: 'Rich Doty'; ccielab@groupstudy.com
> Subject: RE: BGP route-reflector client not installing IBGP routes
>
>
> Rich,
>
> Are you using OSPF as your IGP and have synchronization on? If
> so, there is an extra condition that you must satisfy to meet the
> synchronization rule.
>
> "Paths marked as "not synchronized" in the show ip bgp
<longer-prefixes>
> output. If BGP synchronization is enabled, which it is by default in
> Cisco IOSR Software, there must be a match for the prefix in the IP
> routing table in order for an internal (iBGP) path to be considered a
> valid path. If the matching route is learned from an OSPF neighbor,
its
> OSPF router ID must match the BGP router ID of the iBGP neighbor. Most
> users prefer to disable synchronization using the no synchronization
BGP
> subcommand."
>
>
http://www.cisco.com/en/US/tech/tk648/tk365/technologies_tech_note09186a
> 0080094431.shtml
>
>
> There are many threads that cover this issue, such as the following
one:
>
> http://www.groupstudy.com/archives/ccielab/200209/msg01765.html
>
>
>
> HTH
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> Voice: 847.674.3392
> Fax: 847.674.2625
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Rich Doty
> > Sent: Monday, November 25, 2002 2:11 PM
> > To: ccielab@groupstudy.com
> > Subject: BGP route-reflector client not installing IBGP routes
> >
> > I have a route reflector R5, and 2 route reflector clients R3, R6.
I'm
> > passing IBGP routes, and they are seen by R5/R3 in the BGP table.
They
> > are, however, not being seen as >, or reachable (and injected into
the
> > IP routing table). Both the destination prefix and next-hop are
listed
> > in the IGP routing entries, and the prefixes match. Does anyone have
> any
> > idea why these routes are not being installed?
> >
> > Thanks,
> >
> > Rich
This archive was generated by hypermail 2.1.4 : Tue Dec 03 2002 - 07:23:10 GMT-3