Troubleshooting OSPF Environments

OSPF is a more complex protocol to understand than RIP. As such, there is more risk of problems arising because of the complexity of the protocol. Because OSPF is more hierarchical than other protocols, this offers an opportunity to help troubleshoot problems that may arise; you can isolate problems with a particular area or the interconnectivity between areas more easily. Table 4.7 outlines some of the problems you may face when troubleshooting OSPF.

Table 4.7. OSPF Problems and Resolution

Problem	Solution
OSPF adjacency is not forming between two neighbors.	OSPF is not enabled on the interface. Verify that OSPF is enabled on the interface on the network segment where an adjacency should form. By default, when you add an interface to the OSPF routing protocol, OSPF is disabled for the interface and must be manually enabled.
OSPF adjacency is not forming between two neighbors.	Ping the neighboring router to ensure basic IP and network connectivity. Use the tracert command to trace the route to the neighboring router. There should not be any routers between the neighboring routers.
A virtual link is not forming between two areas.	The problem is a mismatched configuration of password, hello interval, or dead interval. Verify that the virtual link neighbor routers are configured for the same password, hello interval, and dead interval.
A virtual link is not forming between two areas.	Virtual link neighbors are configured for the incorrect transit area ID. Verify that both virtual link neighbors are configured for the same transit area ID and that they are configured to use the correct transit area.
Routing tables are not being updated with OSPF routes, or improper OSPF routes are being received.	If you are not receiving summarized OSPF routes for an area, verify that the area border routers (ABRs) for the area are configured with the proper Destination, Network mask pairs summarizing that area's routes.
Routing tables are not being updated with OSPF routes, or improper OSPF routes are being received.	Not all ABRs are connected to the backbone. Verify that all ABRs are either physically connected to the backbone or logically connect ed to the backbone by using border routers, which are routers that connect two areas without going through the backbone.

Table 4.7 lists only some of the problems that can arise within an OSPF environment. For further troubleshooting information, refer to Microsoft TechNet or the Windows Server 2003 documentation.