Changing the reference bandwidth for the cost on OSPFv3 interfaces

The reference bandwidth for OSPFv3 can be altered, resulting in various costs.
  1. Enter the configure terminal command to access global configuration mode. 
    device# configure terminal
  2. Enter the ipv6 router ospf command to enter OSPFv3 router configuration mode and enable OSPFv3 globally. 
    device(config)# ipv6 router ospf
  3. Enter the auto-cost reference-bandwidth command to change the reference bandwidth. 
    device(config-ospf6-router)# auto-cost reference-bandwidth 500

The following example changes the auto-cost reference bandwidth to 500. 

device# configure terminal
device(config)# ipv6 router ospf 
device(config-ospf6-router)# auto-cost reference-bandwidth 500

The reference bandwidth specified in this example results in the following costs:

  • 10-Mbps port cost = 500/10 = 50
  • 100-Mbps port cost = 500/100 = 5
  • 1000-Mbps port cost = 500/1000 = 0.5, which is rounded up to 1
  • 155-Mbps port cost = 500/155 = 3.23, which is rounded up to 4
  • 622-Mbps port cost = 500/622 = 0.80, which is rounded up to 1
  • 2488-Mbps port cost = 500/2488 = 0.20, which is rounded up to 1

The costs for 10-Mbps, 100-Mbps, and 155-Mbps ports change as a result of the changed reference bandwidth. Costs for higher-speed interfaces remain the same.

Parent topic: OSPFv3