12.9.2 Checking area borders

On an area border router, you can use the show ip ospf operation command to make sure that the AreaBorder appears in the Flags section of the command output.

You can also check whether inter-area route summarization has been applied correctly.

Figure 12-9: Result of executing show ip ospf command
>show ip ospf Date 20XX/07/14 12:00:00 UTC OSPF protocol: ON Domain: 1 Router ID: 172.16.1.1 Distance: Intra Area: 10, Inter Area: 10, External: 150 Flags: <AreaBorder ASBoundary> SPF Interval: 7s, SPF Delay: 3s Graceful Restart: Helper Helper Status : Finished 20XX/02/15 14:12:22 Area Interfaces Network Range State 0 1 - - 10 1 192.168.1/24 Advertise 172.19/18 DoNotAdvertise

Figure 12-9: Result of executing show ip ospf command

>show ip ospf
Date 20XX/07/14 12:00:00 UTC
OSPF protocol: ON
  
Domain: 1
Router ID: 172.16.1.1
Distance:
  Intra Area: 10, Inter Area: 10, External: 150
Flags: <AreaBorder ASBoundary>
SPF Interval: 7s, SPF Delay: 3s
Graceful Restart: Helper
  Helper Status : Finished  20XX/02/15 14:12:22
Area            Interfaces  Network Range      State
0               1           -                  -
10              1           192.168.1/24       Advertise
                            172.19/18          DoNotAdvertise