From: Tony Medeiros (tonygreat@xxxxxxxx)
Date: Wed Sep 20 2000 - 23:58:11 GMT-3
Are you sure this isn't a VLSM to FLSM issue? Remember that IGRP doesn't
send the mask with it's updates. And a route of the same classfull network
MUST have the same mask as the link between the two routers or the routes
aren't going across.
Tony Medeiros CCIE 6172
----- Original Message -----
From: "Dave McFetridge" <dmcfetridge@eccinc.com>
To: <ccielab@groupstudy.com>
Sent: Wednesday, September 20, 2000 6:13 PM
Subject: OSPF to IGRP Redistribution
> I think this is a stupid question But, I actually failed the lab due to
> this.
> I believe this is a general enough question as to not reveal an actual lab
> scenario and violate my confidentiality agreement.
>
> If on a hub router you were doing mutual redistribution between IGRP and
> OSPF and then advertising that information to a router via IGRP, would the
> hub router replace all the routes in his own route table with IGRP routes
> due to the administrative distance of IGRP and then STOP advertising these
> routes to the IGRP router???? I realize at the time admin dist. never
> crossed my mind, but after reflecting on what had happened I started
walking
> through the process and I still believe it should have worked. I
configured
> distribute lists permitting only the IGRP routes to be distributed into
OSPF
> and one denying these same routes and permitting all others to be
> distributed into IGRP.
> Anyway here are my thoughts on how this should have worked, Please correct
> me if I'm wrong. I realize the stress on the lab and constant study can
> sometimes cause you to miss the obvious.
>
> I believe that the OSPF routes in the route table should be initially
> redistributed into IGRP and advertised to the adjacent IGRP router. Then
the
> hub router should populate his own route table with IGRP routes due to the
> lower administrative distance of IGRP. However, The routes in the route
> table still have correct next-hop information and are valid reachable
> routes. I believe the hub router should continue to advertise the routes
to
> the IGRP router since that's what routing protocols do right? They
advertise
> routes learned via the native protocol or redistribution into them. I
can't
> for the life of me think of why this should cause the remote router to
lose
> the routes. The only potential problem I can see is if IGRP was
advertising
> a sub-optimal route that was now preferred over OSPF, but that never came
> into play and split-horizon should prevent the remote router from
> re-advertising the same routes back to the hub making his route info
> invalid.
> Anyway, Sorry for being so long winded, I'm just so frustrated, I was
> sitting with 65 points and couldn't go to troubleshooting due to a stupid
> issue. I can't fault the proctor since at certain times if he were to test
> my configuration it would not have worked. I'm not making excuses, I just
> can't believe after all my hard work I could miss something so stupid.
>
> Thanks in advance,
> Dave McFetridge
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:24:59 GMT-3