RE: set metric on route-map applied to OSPF distribute-list

From: Christian Sica (csica@liweb.net)
Date: Sat Dec 17 2005 - 16:50:02 GMT-3


Gustavo,

Your solution, although creative, IMHO, it won't work. The distribute list
feature is used to determine which routes will be allowed into the RIB and
which will not. Although you can get very detailed and match based on the
OSPF metric, I do not believe any set commands will be of use. It is simply
a filtering mechanism, not a modification mechanism. Since you want both
routes to be available, yet those from AS10 to be preferred, think from the
router's perspective. If you have two routes, both valid and equal cost,
but you want to prefer one over the other, what can you do? Yes modifying
the metric is the first and easiest choice, but that is not the only one.
If you cant modify the metric, try modifying the administrative distance.

HTH,
Christian

More info on Using Distribute lists:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120
limit/120s/120s24/routmap.htm

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Saturday, December 17, 2005 2:32 PM
To: Cisco certification
Subject: set metric on route-map applied to OSPF distribute-list route-map
XXXX in

Hello

I'm trying to make OSPF decide between two paths without changing any
interface values.

 The same routes are coming from both paths(two different interfaces),
but only the ones tagged with 10 are to be decided upon one interface or
the other. When one path is not available, the other path should kick
in.

To do this I'm trying to build a route-map like this.

router ospf 1

 router-id 150.1.5.5

distribute-list route-map AS10-PREFER in

route-map AS10-PREFER permit 10

 match ip next-hop R4

 match tag 10

 set metric 20

!

route-map AS10-PREFER permit 20

 match ip next-hop R3

 match tag 10

 set metric 30

!

route-map AS10-PREFER permit 30

This, theoretically would allow me to enter on the RIB the routes with
smaller metric.

The problem is that OSPF keeps ignoring my set statements and keeps the
routes always with metric 20, thus allowing load sharing to the tagged
paths.

The target routes are E2, but shouldn't the route-map act upon their
metric nonetheless?

Or because I'm using the route-map on a distribute-list the set commands
are not valid?

TIA

Gustavo Novais



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