show ip ospf interface brief displays concise information about OSPF-enabled interfaces, including each interface’s process ID, area, IP address and mask, cost, state, and neighbor counts. section 18.1.3 section 18.5
Checking interface costs
On R1, the command initially shows Gi0/0 and Fa1/0 with cost 1. After the OSPF reference bandwidth changes to 1000 Mbps, Gi0/0 remains at cost 1 while Fa1/0 becomes cost 10, helping OSPF distinguish their bandwidths. section 18.1.3
R1# show ip ospf interface brief
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Gi0/0 1 0 10.0.0.1/30 1 DR 1/1 #1
Fa1/0 1 0 10.0.0.5/30 1 DR 1/1 #1
R1# configure terminal
R1(config)# router ospf 1 #2
R1(config-router)# auto-cost reference-bandwidth 1000 #3
% OSPF: Reference bandwidth is changed. #4
Please ensure reference bandwidth is consistent
across all routers. #4
R1(config-router)# do show ip ospf interface brief
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Gi0/0 1 0 10.0.0.1/30 1 DR 1/1 #5
Fa1/0 1 0 10.0.0.5/30 10 DR 1/1 #5
#1 G0/0 and F1/0 have identical costs: 1.
#2 Enters OSPF router config mode
#3 Sets the reference bandwidth to 1000 Mbps (1 Gbps)
#4 IOS gives a warning message.
#5 G0/0’s cost remains at 1, but F1/0’s cost is now 10.
Use the CLI listing to inspect the command’s fields and compare interface costs before and after changing the OSPF reference bandwidth. section 18.1.3
