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Multiple equal cost paths learnt via ospf

Hello folks,

I have two equal cost paths learnt via ospf. But, Only one shows up in the routing table. Since it is in area 0. The other path is in area 1, and does not show up in the routing table eventhough the metric/cost is the same.

Is there a way i could load balance between the two paths??

Thanks

3 REPLIES

Re: Multiple equal cost paths learnt via ospf

Use the 'maximum-paths 2' command under OSPF to allow more than one path to the routing table. OSPF allows only equal cost load balancing.

eg

Router(config)#router ospf 1

Router(config-router)#maximum-paths 2

Then if you have cef enabled, you can load-balance per-packet by 'ip load-sharing per-packet' (see link: http://www.cisco.com/en/US/tech/tk648/tk365/technologies_tech_note09186a0080094806.shtml#cefloadshare ).

Hope it helps.

Steve

Gold

Re: Multiple equal cost paths learnt via ospf

I wouldn't suggest doing per packet load sharing unless you've tested it, and know that it will give you better performance. In general, the per flow load sharing done with cef is very good at sharing traffic, most of the time giving you at least a 60/40 split. The out of order packets you are likely to get with per packet load sharing will probably cost you more in performance than the gain from the "more equal" load sharing.

:-)

Russ

New Member

Re: Multiple equal cost paths learnt via ospf

Thanks for the info,

ospf does not have a problem in load balancing between two equal costs paths, the problem here is that one of the path is not in area 0 , but in area 1 and as a result even though the cost is the same, i do not see it load balance.

any ideas??

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