Re: [OSPF] ECMP from different areas of External Routes

If nexthops to the same destination prefix, are of same cost, path-type and same area, then ONLY ECMP comes into play else not. Now in case of External Routes(Refer Section 16.4) ecmp depends upon how you resolve the nexthops w.r.t reachibility to ASBR(incase the forwarding address is set to zero) else depends upon the nexthop through which the Forwarding Address can be reached. However the criterion (cost,path-type,area) still holds decide whether during SPF the same prefix should be installed as ECMP(multiple nexthops).

Thanks,

Jishnu

Night after night
Going round and round my brain
His dream is driving me insane.
In the corner of some foreign field
The gunner sleeps tonight.
What's done is done.
We cannot just write off his final scene.
Take heed of his dream.
Take heed

From: ospf-bounces at ietf.org [mailto:ospf-bounces at ietf.org] On Behalf Of Pranjal Chakravarty
Sent: Thursday, June 12, 2008 12:37 PM
To: ospf at ietf.org
Subject: [OSPF] ECMP from different areas of External Routes

I have a router with zebos implementation of ospf .

Is ECMP is allowed in the router if the routes are learned from two diffrernt non backbone areas(Same cost),Or only one route will be installed in the router .

The Route which is learnt from a higher area id will be installed in the router or both equal cost routes should be installed in the router.

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