From: James (james@towardex.com)
Date: Wed Oct 13 2004 - 13:36:39 GMT-3
On Wed, Oct 13, 2004 at 10:10:26AM -0400, ccie2be wrote:
> Now, I noticed that R1 is only sending 3 routes to sw2 but I'm not sure why.
> R1's route table is the same as R3's and both are redist the same routes into
> rip. Could this be a timing issue? In other words, is this possibly because
> when R3 redist it's isis routes into rip and advertises them to sw2, sw2 in
> turn advertises these same routes to R1 and because of split horizon R1
> doesn't advertise these same routes back to SW2?
>
> If this is the case, then why are there any exceptions? Why does sw2 have 2
> paths for 3 routes instead of just 1 path for these routes?
I think you are bumping into the similar problem I had a while ago with a bit
same topology (ISIS->RIP redist on two routers, and two routers and a L3 switch
are sitting on shared ethernet running RIP, just like yours). If I recall
correctly, the split horizon +/- route poisoning issue of RIP keeps the routing
table on the devices pretty unstable (e.g. routes would flap, all isis->rip
redistributed routes would appear with one router as nexthop, then all flap
again, etc). As far as why it does that, I think your assertion above may be is
correct..
Anyway the solution that I used to fix this was to make switch the
"authoritative" rip router on both routers. I've set distance to 114 on the
switch's address, and 125 for routes from other router. This made RIP on each
router to have higher pref on the routes via the switch instead. Switch going
down would make it select the other router.
This had been a while since I did this, so I'm sure I may be missing some
memory here, in which someone can point additional insights to this matter.. :)
HTH,
-J
>
> Any insight would be greatly appreciated.
>
> Thanks, Tim
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
-- James Jun TowardEX Technologies, Inc. Technical Lead Network Design, Consulting, IT Outsourcing james@towardex.com Boston-based Colocation & Bandwidth Services cell: 1(978)-394-2867 web: http://www.towardex.com , noc: www.twdx.net
This archive was generated by hypermail 2.1.4 : Sat Nov 06 2004 - 17:11:47 GMT-3