MPLS FRR

Answered Question
Mar 26th, 2009

Hello:

I use IOS code 7200 Software (C7200-SPSERVICESK9-M), Version 12.2(33)SRC3

at default MPLS FRR works fine

when I shutdown pos interface on primary path, FRR works fine, but after I bring back pos interface, I noticed tu1 still use backup path

until I shut and no shut tu1

anyone could shred a light?

thx,

~mike

I have this problem too.
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Correct Answer by Giuseppe Larosa about 7 years 10 months ago

Hello Mike,

this is normal the best path is not used as soon as it is up again, but when the next optimization time is triggered.

you should use show mpls traffic-eng tunnels brief

to see this.

see

http://www.cisco.com/en/US/docs/ios/mpls/configuration/guide/mp_te_frr_node_prot_ps6922_TSD_Products_Configuration_Guide_Chapter.html#wp1382260

Hope to help

Giuseppe

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Harold Ritter Thu, 03/26/2009 - 12:15

James,

You can also do a "mpls traffic-eng reoptimize" If you want to force reoptimization to take place right away instead of waiting for the reoptimization timer to expire.

Regards

baradasabut Mon, 03/30/2009 - 11:15

Hi Ritter,

By any chance, is it possible to schedule re-optimize at random intervals ?

Regards,

Harold Ritter Mon, 03/30/2009 - 18:07

Barada,

It will happen after the re-optimize timer times out, which one hour (3600 seconds) by default.

Regards

holden.matthew Tue, 03/31/2009 - 19:36

could you not also solve your problem by using

mpls traffic-eng reoptimize events link-up

??

Harold Ritter Tue, 03/31/2009 - 19:47

Matthew,

This would certainly work. It boils down to how quickly you want your path to be reoptimized vs. network stability.

Regards

vijaykumarArumugam Fri, 04/03/2009 - 11:59

Hi Mike,

Instead of dynamic path option, configure an explicit path with "192.168.3.1" as strict hop and try the scenario.

In this case, when pos interface on primary path goes down the traffic will be rerouted via backup tunnel and the primary path will be retried for every 30 seconds. When the interface is back up, primary path signaling will succeed and tunnel will no longer use the backup path.

When tunnel uses the backup tunnel, "show mpls traffic-eng fast database" will display it's status as "active".

With dynamic path option, the tunnel will calculate a path which will be same as the backup tunnel path and it'll look like it's using the backup tunnel. To use the best path you've to trigger reoptimization (manual/periodic/event-linkUp).

Thanks,

Vijay

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