From: David Hiers (dhiers@flatrock.com)
Date: Thu Nov 07 2002 - 15:51:35 GMT-3
Hi,
I am trying to select routes from different protocols based on cost alone. I have set the administrative distance of OSPF, ISIS, and EIGRP to 109, and the routes are selected as if the ADs are at their defaults. Here's an example showing r3, which gets the same route from ISIS and OSPF:
The ospf link is dead now, and ISIS shows the route:
r3#sir 170.10.19.0
Routing entry for 170.10.19.0/26
Known via "isis", distance 109, metric 30, type level-2
Redistributing via isis, eigrp 33
Advertised by eigrp 33 level-2
Last update from 170.10.35.5 on Serial0, 00:00:03 ago
Routing Descriptor Blocks:
* 170.10.35.5, from 170.10.15.1, via Serial0
Route metric is 30, traffic share count is 1
bring up the ospf link here:
*Mar 1 03:41:07.735: RT: closer admin distance for 170.10.19.0, flushing 1 routes
*Mar 1 03:41:07.739: RT: add 170.10.19.0/26 via 170.10.24.4, ospf metric [109/1000000]
r3#sir 170.10.19.0
Routing entry for 170.10.19.0/26
Known via "ospf 1", distance 109, metric 1000000, type extern 2, forward metric 74
Redistributing via eigrp 33
Advertised by eigrp 33
Last update from 170.10.24.4 on Serial1, 00:01:08 ago
Routing Descriptor Blocks:
* 170.10.24.4, from 222.5.5.5, 00:01:08 ago, via Serial1
Route metric is 1000000, traffic share count is 1
There seems to be some other tie-breaker in effect here, especially when you consider the huge cost on the OSPF route. Perhaps AD is ALWAYS a tie breaker, even if you try to force the issue.
I get similar results with EIGRP as well.
Has anyone ever seen this behavior?
David
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David Hiers
Support Engineer
Flatrock, Inc.
1505 Gideon St, Suite 600
Portland, OR 97202
V: 503 963 3719
F: 503 963 3799
dhiers@flatrock.com
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