From: Landon Fitts (lafitts@cisco.com)
Date: Fri Oct 14 2005 - 20:27:20 GMT-3
I have a question on the various methods available to prevent EIGRP
routes that are redistributed into OSPF at two different ASBRs from
being installed into the route table of those same ABSRs when relearned
from OSPF. I was able to use a "distribute-list <acl> in" under the ospf
process to successfully achieve this, but I couldn't get it to work using
a route-map on the redistribution statement matching on the tagged eigrp
networks. Using the route-map with tagging method, the routing table
would go back and forth between installing an E2 route and a EX route on
the ASBRs every time I cleared the route table.
To make this clearer below is my topology:
|---R3-----|
R1-----R2-----SW-----| |-----R5
<mailto:lafitts@cisco.com> |---R4-----|
Scenario:
- R1 and R2 are running EIGRP AS-2 between them
- R3, R3, and R4 are running EIGRP AS-1 between them
- R3, R4, and R5 are running OSPF AREA-0 over FR between them
- R2 is mutually redistributing EIGRP AS-1 & AS-2
- R3 and R4 are mutually redistributing OSPF and EIGRP
Problem:
Networks from AS-2 will be seen as EIGRP external routes at R3 & R4, so
when these networks are relearned back from R5 via OSPF the route table
at R3 and R4 will install the E2 routes because of the lower admin
distance. This will not be a problem for the networks learned from
AS-1 via R2, because at R3 & R4 those networks will be seen as internal
EIGRP routes.
Route Redistribution at multiple redistribution points has never been an
easy
topic for me, but this scenario seems to add more complications. Can any
of you routing experts shed some light on this for me?
Thanks,
Landon
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