From: Brian McGahan (brian@cyscoexpert.com)
Date: Mon Nov 25 2002 - 20:47:41 GMT-3
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