Useful commands to verify OSPF include the following:
- show ip ospf neighbor - Command to verify that the router has formed an adjacency with its neighboring routers. If the router ID of the neighboring router is not displayed, or if it does not show as being in a state of FULL, the two routers have not formed an OSPF adjacency.
- show ip protocols - Command provides a quick way to verify vital OSPF configuration information. This includes the OSPF process ID, the router ID, networks the router is advertising, the neighbors the router is receiving updates from, and the default administrative distance, which is 110 for OSPF.
- show ip ospf - Command is used to display the OSPF process ID and router ID as well as the OSPF SPF and OSPF area information.
- show ip ospf interface - Command provides a detailed list for every OSPF-enabled interface and is very useful to determine whether the network statements were correctly composed.
- show ip ospf interface brief - Command is useful to display a summary and status of OSPF-enabled interfaces.
Figures 1 to 5 display the corresponding output each verification command entered on R1.
Use the Syntax Checker in Figure 6 to verify the neighbor adjacency, vital OSPF configuration information, and to display a summary of OSPF enabled interfaces on R2.
Use the Syntax Checker in Figure 7 to verify the neighbor adjacency, vital OSPF configuration information, and to display a summary of OSPF enabled interfaces on R3.