May 05

OSPF is not using the best route

If you are finding that OSPF is not using the fastest links on your network, it probably sees your 100mbps, 1G, and 10G interfaces as the same cost, 1. To get more granular route selection from OSPF, you need to change your reference-bandwidth statement. You want your highest bandwidth interface to have a cost of 1. If you uses 10,000 in the statement below, it would give your 10G interfaces a cost of 1.

**YOU MUST ADD THIS COMMAND TO EVERY ROUTER RUNNING OSPF IN YOUR NETWORK**

In Router Configuration mode use the following command

auto-cost reference-bandwidth

= The largest bandwidth interface, Example, 10G interface would be 10000

The statement above works for both Brocade and Cisco.