7.5 Adjacency Troubleshooting Flashcards
show ip protocols
to view OSPF configuration information, such as:
The OSPF process ID.
The OSPF router ID for the current router.
Configured networks and areas for the process.
IP addresses of neighbor routers.
show ip ospf
to view OSPF information, including:
The process ID.
The local router ID and its role (such as DR or BDR).
Configured areas.
show ip ospf neighbor
to view information about neighbor OSPF routers, including:
Router ID of the neighbor router.
Neighbor state or status. The full state indicates that the DR/BDR election has occurred and routers are exchanging routing information.
The role of the neighbor (DR, BDR, DROTHER).
Time remaining before the neighbor is declared missing if a hello packet is not received.
The IP address of the neighbor.
The local interface used to reach the neighbor.
show ip ospf interface
to view interfaces that are running OSPF, including the following information:
Interface status and IP address assigned to the interface.
Area number.
Process ID.
Router ID.
The router ID and IP address of the DR and BDR on the network.
Hello and dead timer settings.
Adjacent routers.
debug ip ospf events
to view debugging information about hello exchanges, DR selection information, SPF calculation, and errors related to negotiating adjacency.
Use debug ip ospf hello to view only hello packet information.
Use debug ip ospf adj to view adjacency information.
What does the command debug ip ospf events do
Shows a list of errors
What does the error
OSPF: mismatched hello parameters from 10.0.0.1
OSPF: Dead R 20 C 40, Hello R 5 C 5
Mask R 255.255.255.0 C 255.255.255.0
mean
Hello timer, dead timer, or subnet mask mismatch detected. In the following example, the dead timer intervals do not match:
R (received) = 20, C (configured) = 40
What does the error
OSPF: hello packet with mismatched E bit
Area types (not area numbers) configured on each router do not match. The E bit is also called the stub area flag.
What does the error
Neighbor Down: Dead timer expired
mean
An expected hello timer has not been received. When the dead timer reaches 0, it is assumed that the neighbor router has gone down. The dead timer resets itself each time a hello packet is received.
