From: Dave McFetridge (dmcfetridge@xxxxxxxxxx)
Date: Wed Sep 20 2000 - 22:13:47 GMT-3
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
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