4.5 Verifying OSPF Operation
4.5.2 Clear and debug commands
The following commands and their associated options can be used when troubleshooting OSPF:

To clear all routes from the IP routing table use the following command:

router#clear ip route *

To clear a specific route from the IP routing table use the following command:

router#clear ip route A.B.C.D
A.B.C.D Destination network route to delete

To debug OSPF operations use the following debug options:

router#debug ip ospf ?

adj OSPF adjacency events
events OSPF events
flood OSPF flooding
lsa-generation OSPF lsa generation
packet OSPF packets
retransmission OSPF retransmission events
spf OSPF spf
tree OSPF database tree