The objective of this lab exercise is for you to configure OSPF on three routers using more than one area. You will then use the passive-interface default command to turn off Hellos on all interfaces for RouterA and then enable them on the Serial interface on that router.
Multi-Area OSPF is a core ICND2 topic and you must understand how to use the passive interface command. I have provided show runs and test commands where appropriate.
This lab is suitable for both ICND2 and CCNA certification exam preparation.
This lab has a difficulty rating of 7/10.
When you are ready for your certification exam, you should complete this lab in no more than 15 minutes.
Please use the following topology to complete this lab exercise:
Configure the topology above. Test by pinging from RouterA to RouterB, then RouterB to RouterC. You will not be able to ping from A to C until you have configured OSPF.
Configure OSPF between all routers with each interface/subnet in the correct area.
Make all interfaces on RouterA passive and then enable Serial0/0.
Check your configurations.
The passive-interface command produces different results for different protocols. The interface for OSPF will no longer send Hellos and so an adjacency will not form on this link. LSAs will be sent however. In this lab, I’ve set all OSPF interfaces to be passive but then enabled the Serial interface.
Show Runs RouterA hostname RouterA ! interface Loopback0 ip address 192.168.1.1 255.255.255.252 ! interface Serial0/0 ip address 10.0.0.5 255.255.255.252 clock rate 2000000 ! router ospf 1 log-adjacency-changes passive-interface default no passive-interface Serial0/0 network 10.0.0.4 0.0.0.3 area 0 network 192.168.1.0 0.0.0.3 area 2 RouterB hostname RouterB ! interface Serial0/0 ip address 10.0.0.6 255.255.255.252 clock rate 2000000 ! interface Serial0/1 ip address 172.16.1.1 255.255.255.252 clock rate 2000000 ! router ospf 1 log-adjacency-changes network 10.0.0.4 0.0.0.3 area 0 network 172.16.1.0 0.0.0.3 area 1 RouterC ! hostname RouterC ! interface Serial0/0 ip address 172.16.1.2 255.255.255.252 clock rate 2000000 ! interface FastEthernet0/1 no ip address shutdown duplex auto speed auto ! router ospf 1 log-adjacency-changes network 172.16.1.0 0.0.0.3 area 1
RouterA#show ip prot Routing Protocol is “ospf 1” Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Router ID 192.168.1.1 It is an area border router Number of areas in this router is 2. 2 normal 0 stub 0 nssa Maximum path: 4 Routing for Networks: 10.0.0.4 0.0.0.3 area 0 192.168.1.0 0.0.0.3 area 2 Reference bandwidth unit is 100 mbps Passive Interface(s): FastEthernet0/0 FastEthernet0/1 Loopback0 Routing Information Sources: Gateway Distance Last Update 10.0.0.6 110 00:00:04 192.168.1.1 110 00:05:54 Distance: (default is 110)