----- Original Message ----- From: "Peter van Oene" To: Sent: Wednesday, December 26, 2001 7:47 PM Subject: Re: OSPF into iBGP with Sync [7:30126]
> To my knowledge, this is purely a cisco implementation issue and you'd need > to look at the code or ask the coders what their particular intention > was. OSPF didn't play much of a role in transit networks during the time > when synchronization was a relevant option as far as I know so I doubt > there was very extensive testing done on this particular feature. I would > expect this was just an additional check to ensure route > authenticity. Given this feature is many years antiquated, I'm surprised > so many folks try and make it work. > unfortunately, if it were as simple as just that, I could just deal with it. However, when it affects my ability to propagate iBGP routes to an eBGP neighbor, and the restriction is sync on all but the route reflector router, a solution has to be figured out. If it were on the lab exam, I'd probably disable sync if I got desparate (and kiss some points goodbye) if I didn't know the answer. Therein lies a good point for the lab exam: Know what your contigency (backup) plan is if you can't figure out the solution that you're being pointed to so that you can at least get the darned thing running and you can move on to the next step. > pete > > > At 06:23 PM 12/26/2001 -0500, John Neiberger wrote: > >We discovered something on the CCIE list recently and I'm > >wondering if anyone might be able to explain the reasoning > >behing this behavior. > > > >BGP synchronization rules require that if an iBGP peer is to > >advertise a route learned via iBGP, it must have that prefix > >*and* the next hop for that route in the routing table already. > > > >An interesting added complexity to this occurs if your IGP is > >OSPF. If the router in question has learned these prefixes via > >OSPF, then the advertising router ID in the OSPF database must > >match the router ID of the iBGP peer that advertised the route. > > > >Has this behavior caused any problems for any of you? Do you > >know why the synchronization rules have a special case for OSPF > >and not other routing protocols? > > > >I was working with someone else on a practice lab and we ran > >into this issue. We were both going nuts trying to figure out > >why the iBGP routes weren't synchronizing and this turned out > >to be the cause. > > > >Any thoughts? > > > >Thanks, > >John > > > >________________________________________________ > >Get your own "800" number > >Voicemail, fax, email, and a lot more > >http://www.ureach.com/reg/tag _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=30283&t=30126 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
