121
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.
5.
In a stub area, all routers attached are configured with the
stub
command. In an NSSA area, all
routers attached are configured with the
nssa
command.
6.
If a virtual link is configured, use the
display ospf vlink
command to verify the state of the virtual
link.