Lab 5.6.1 OSPF NSSA with Route Filtering

Objectives:  

  • Use OSPF with the NSSA option to redistribute RIP routes into the OSPF core via a stub transit area.

Scenario:  

You have a RIP routing domain and an OSPF Area 0 with redistribution.  You need to reduce the number of OSPF routes that enter your OSPF Stub Area. You must allow the redistributed routes into the core.  You must also filter some of your RIP routes from entering the core area.

Lab Task:

  1. Cable the lab and all interfaces as shown in the diagram. You will use loopbacks for the RIP networks.

  2. Configure OSPF routing on all routers.

Router-a(config)#router ospf 1 
Router-a(config-router)#network 206.202.0.0 0.0.0.255 area 0

Router-b(config)#router ospf 1 
Router-b(config-router)# network 206.202.0.0 0.0.0.255 area 0 Router-b(config-router)# network 206.202.1.0 0.0.0.255 area 1

Router-c(config)interface loopback 1 
Router-c(config-if)ip address 192.168.1.1 255.255.255.0 Router-c(config-if)interface loopback 2 
Router-c(config-if)ip address 192.168.2.1 255.255.255.0 Router-c(config-if)interface loopback 3 
Router-c(config-if)ip address 192.168.3.1 255.255.255.0 Router-c(config)interface loopback 4 
Router-c(config-if)#ip address 192,168.4.1 255.255.255.0 
Router-c(config-if)interface loopback 5 
Router-c(config-if)ip address 192.168.5.1 255.255.255.0 Router-c(config)router ospf 1 
Router-c(config-router)#network 206.202.1.0 0.0.0.255 area 1 
Router-c(config-router)#router rip 
Router-c(config-router)#network 192.168.1.0 Router-c(config-router)#network 192.168.2.0 Router-c(config-router)#network 192.168.3.0 Router-c(config-router)#network 192.168.5.0

  1. Verify that OSPF is configured correctly and all OSPF routes are listed in the routing table. On Router C the 192.168.XX.XX networks should be directly connected, but not listed in the routing table of the other routers.
  2. On Router C add the following command to redistribute all the rip routes into your OSPF Area 0:
    Router-c(config)router ospf 1 Router-c(config-router)#redistribute rip subnets
  3. On Router A, issue the command show ip route to see if the rip routes are being redistributed into the OSPF Area 0.

  4. On Router B, add the following command to properly summarize the RIP routes into the OSPF Area 0.
    Router-b(config)router ospf 1 Router-b(config-router)#summary-address 192.168.0.0 255.255.252.0 not-advertise
  5. Issue the command show ip route from Router A. Record your results below.
  6. Go to Router B and Router C and add the following command:
  7. Router-b(config)router ospf 1 Router-b(config-router)#area 1 nssa
    Router-c(config)router ospf 1 Router-c(config-router)#area 1 nssa

  8. Issue the commands show ip route from Router A and Router B. Record your results below.