121
Flags: 0x1008c OrigNextHop: 13.13.13.1
Label: NULL RealNextHop: 13.13.13.1
BkLabel: NULL BkNextHop: 24.24.24.2
Tunnel ID: Invalid Interface: GigabitEthernet2/0
BkTunnel ID: Invalid BkInterface: GigabitEthernet1/0
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, verify 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 can have different network segments and masks).
Solution
1.
Use the
display ospf peer
command to verify OSPF neighbor information.
2.
Use the
display ospf interface
command to verify OSPF interface information.
3.
Ping the neighbor router's IP address to verify that the connectivity is normal.
4.
Verify OSPF timers. The dead interval on an interface must be at least four times the hello interval.
5.
On an NBMA network, use the
peer ip-address
command to manually specify the neighbor.
6.
At least one interface must have a router 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.
Solution
1.
Use the
display ospf peer
command to verify neighbor information.
2.
Use the
display ospf interface
command to verify OSPF interface information.
3.
Use the
display ospf lsdb
command to verify the LSDB.
4.
Use the
display current-configuration configuration ospf
command to verify area configuration. If
more than two areas are configured, at least one area is connected to the backbone.
