Lab 4.4.4 OSPF Point-to-Multipoint Lab

Objectives:

  • Configure OSPF to function correctly in a non-broadcast environment.

Equipment Requirements:

  • Two Routers
  • One Switch with two VLANS set or two switches or two hubs
  • Two workstations

Scenario:

You are the network administrator of the above network, which has 3 sites, connected via a hub and spoke frame-relay cloud. Both Biloxi and Chicago have PVC's to Abilene. It is well documented that OSPF behaves quite differently in a Non-broadcast environment as opposed to a broadcast environment. You have decided to implement a point-to-multipoint configuration.

Step 1

Cable the lab as shown above. The device used to simulate a frame relay cloud will be the Adtran unit.

Step 2

Configure the serial interfaces to match the addressing scheme shown above. Use the first available address for your Ethernet interfaces. Use multipoint subinterfaces on the serial connections into the frame cloud. To configure the subinterfaces issue the following commands:

Abilene(config)#interface serial 0
Abilene(config-if)#encapsulation frame-relay IETF
Abilene(config-if)#no shutdown

Abilene(config)#interface serial 0.101multipoint
Abilene(config-subif)#ip address 172.16.4.1 255.255.255.0

Follow this same procedure with different addresses on the other two router serial interfaces.

Step 3

Why did we choose to use multipoint interfaces?

Step 4

Now it is time to complete the frame-relay configuration. On Abilene, you need to set up the DLCI for both connections. The connection to Biloxi is DLCI 101 and the connection to Chicago is DLCI 102. Issue the following commands on the sub-interface:

Abilene(config-subif)#frame-relay interface-dlci 101
Abilene(config-subif)#frame-relay interface-dlci 102

Biloxi(config-subif)#frame-relay map ip 192.168.10.0 101 broadcast
Biloxi(config-subif)#frame-relay map ip 192.168.12.0 101 broadcast

Chicago(config-subif)#frame-relay map ip 192.168.10.0 102 broadcast
Chicago(config-subif)#frame-relay map ip 192.168.11.0 102 broadcast

Step 5

Enable OSPF routing on each router. Advertise all networks directly connected to your router.

Step 6

Examine the routing tables of each router. Are any entries missing? Can you ping everywhere? Report your findings.

Step 7

Now it is time to make OSPF behave correctly! Issue the following command on each subinterface of each router:

Router(config-subif)#ip ospf network point-to-multipoint

Step 8

Go back and verify complete routing tables and verify connectivity. Report your findings.