Multi-area OSPF 2

By certskills May 4, 2016 09:05

A router configuration can enable OSPF on an interface directly using the ip ospf interface subcommand. In fact, the configuration is more direct and obvious than the old traditional use of the OSPF network subcommand. This lab combines OSPF interface configuration with a multi-area OSPF design, with a little extra configuration related to OSPF router IDs thrown in for variety.


Configure multi-area OSPFv2 (that is, OSPF for IPv4) on the four routers shown in the figure. Use the area design shown in the figure. The configuration should use the interface subcommand ip ospf to enable OSPF on each interface, and should use no network commands in OSPF configuration mode. The specific rules for this lab are:

  • Use an OSPF process-ID of 50 on all routers
  • Use only ip ospf interface subcommands to enable OSPF on an interface
  • Use the following OSPF router IDs, and make each router use the method listed below when the router chooses its router ID:
    • Core1: (explicitly configured)
    • Core2: (explicitly configured)
    • Branch1: (Based on interface loopback0 address of
    • Branch2: (Based on interface loopback0 address of
  • Use all default OSPF parameters unless otherwise requested.
  • Assume all device interfaces shown in the lab are up, working and with correct IP addresses assigned.


Figure 1: Multi-area OSPF Topology


Initial Configuration

Example 1, 2, 3 and 4 show the beginning configuration state of Core1, Core2, Branch1 and Branch2.

Example 1: Core1 Config


Example 2: Core2 Config


Example 3: Branch1 Config


Example 4: Branch2 Config


Answer on Paper, or Maybe Test in Lab

Next, write your answer on paper. Or if you have some real gear, or other tools, configure the lab with those tools.

To test your solution, if you happen to try it with VIRL or real gear, you can verify that the correct configuration has been entered by verifying a couple of different items. First, check the OSPF neighbor relationships with the show ip ospf neighbor command. The two core routers should list two neighbors each, and the two branch routers should list one neighbor each. Check the routing tables, using the show ip route command, to ensure that all known networks have been learned on each device. Each router should list five subnets, with 3 subnets learned by OSPF.

From the branch routers, also test connectivity with the ping command. For instance, on router Branch1, use the ping source command to issue an extended ping from Branch1’s G0/2 interface IP address ( to router Branch2’s G0/2 interface address (


Do this Lab with Cisco’s VIRL

You can do these labs on paper and still get a lot out of the lab. As an extra help, we have added files for the Virtual Internet Routing Lab (VIRL) software as well. The .VIRL file found here is a file that when used with VIRL will load a lab topology similar to this lab’s topology, with the initial configuration shown in the lab as well. This section lists any differences between the lab exercise and the .VIRL file’s topology and configuration.

Download this lab’s VIRL file!


The virl topology matches this lab topology exactly.

Answers: Login Security 1
Answers: Multi-area OSPF 2
By certskills May 4, 2016 09:05
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  1. James Ryan Dfaper May 13, 22:52

    I would like to know if we can have the lab format available also in CML?

    Reply to this comment
    • certskills Author May 15, 07:36

      Hi James,
      CML Personal is the latest version of what was formerly called VIRL. Per the docs, the older VIRL file should be compatible and opened correctly in the new CML Personal edition. I’ve not tried it yet myself, but if you try, let me know how it goes.

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