OSPF and unequal cost load balancing

by arul on June 22, 2010

Quick question regarding OSPF and unequal cost load balancing.
I know that OSPF does not support this and have realised that i can either adjust the costs for the interface or reconfigure to EIGRP.Are there any other options?

{ 2 comments… read them below or add one }

Kumar June 22, 2010 at 9:45 pm

Thats the best you can do by tweaking costs, which makes it equal cost load balancing. Or reconfigure the entire RP to EIGRP (which probably is a major change in your network if its big).
Even with equal costs, if you have two links one that is a T1, and one that is 56k, you will experience congestion across the 56k, as both are considered equal costs by OSPF. It doesnt share the traffic (balance it out) across both the links according to the bandwidth of the link. (Which EIGRP can).
You can instead use PBR to send traffic from specific subnets across each link (or even based on applications). This will over ride routes populated via OSPF on the router.

karan June 22, 2010 at 9:45 pm

You could use MPLS TE to achieve that goal but that would be another story.

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