HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual page 772

IP Routing—Configuring RIP, OSPF, BGP, and PBR
Troubleshooting Routing
13-158
3. View the OSPF interfaces (show ip ospf interface) and verify that all
interfaces that should be running OSPF are listed. Also make sure that the
interfaces are up and active.
If an interface that should be running OSPF is not, you have found your
problem. Move to the OSPF configuration mode context and enable OSPF
on the interface's network. For example:
ProCurve(config-ospf)# network 192.168.3.0 0.0.0.255 area 1
Take care to place the network in the correct area. Remember that the
network for the interface's primary address must run OSPF.
If an interface is down, troubleshoot it as described in the Basic Manage-
ment and Configuration Guide, Chapter 6: Configuring the Data Link
Layer Protocol for E1, T1, and Serial Interfaces.
4. Verify that the area for the interface in question is correct. If an interface
is in the wrong area, it will not establish full adjacency with neighboring
routers. If this is an internal router, all networks should be in the same
area. If necessary, remove and re-add an incorrectly defined network:
ProCurve(config-ospf)# no network 192.168.3.0 0.0.0.255 area 10
ProCurve(config-ospf)# network 192.168.3.0 0.0.0.255 area 1
5. Next, check the OSPF neighbors (show ip ospf neighbor). The router
should have established full adjacency with all connected OSPF routers.
For point-to-point links, the neighbor state should be "FULL/PPTP."
If the state remains in EXSTART or EXCHANGE, one router cannot
receive the other router's database. This problem could be caused by:
• Incompatible MTU—The router with the smaller MTU will reject over-
size packets from its neighbor and so may not receive the neighbor's
database. It will stay in the EXSTART state. The neighbor with the
larger MTU will continue sending packets and remain in the
EXCHANGE state. If you are troubleshooting an inactive network and
can view debug messages, enter debug ip ospf and look for messages
such as those shown in Figure 13-37. Set the MTU on the interfaces
to the same value. You might need to reset the OSPF process.