165
a.
Display the OSPF neighbor information of Switch A. Switch A has removed its neighbor
relationship with Switch B; therefore, no information is output.
<SwitchA> display ospf peer
OSPF Process 1 with Router ID 192.168.1.40
Neighbor Brief Information
Troubleshooting OSPF configuration
No OSPF neighbor relationship established
Symptom
No OSPF neighbor relationship can be established.
Analysis
If the physical link and lower layer protocols work well, check OSPF parameters configured on
interfaces. Two neighbors must have the same parameters, such as the area ID, network segment
and mask (a P2P or virtual link may have different network segments and masks).
Processing steps
1.
Display OSPF neighbor information using the
display ospf peer
command.
2.
Display OSPF interface information using the
display ospf interface
command.
3.
Ping the neighbor router’s IP address to check connectivity.
4.
Check OSPF timers. The dead interval on an interface must be at least four times the hello
interval.
5.
Using the
peer ip-address
command to specify the neighbor manually is required on an
NBMA network.
6.
At least one connected interface must have a DR priority higher than 0 on an NBMA or a
broadcast network.
Incorrect routing information
Symptom
OSPF cannot find routes to other areas.
Analysis
The backbone area must maintain connectivity to all other areas. If a router connects to more than
one area, at least one area must be connected to the backbone. The backbone cannot be
configured as a Stub area.
In a Stub area, all routers cannot receive external routes, and all interfaces connected to the Stub
area must belong to the Stub area.
