December 08, 2013

Lab 05: OSPF Virtual-link

Configure OSPF in the network. We need a virtual link to connect AREA 0 and AREA 2. This is R2's configuration:

router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 area 1 virtual-link 3.3.3.3
 network 10.0.0.0 0.0.0.3 area 0
 network 10.0.0.4 0.0.0.3 area 1

This is R3's configuration:

router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 area 1 virtual-link 2.2.2.2
 network 10.0.0.4 0.0.0.3 area 1
 network 10.0.0.8 0.0.0.3 area 2

R4's routing table after virtual-link is established:

R4#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     10.0.0.0/30 is subnetted, 3 subnets
C       10.0.0.8 is directly connected, Ethernet0/0
O IA    10.0.0.0 [110/30] via 10.0.0.9, 00:01:48, Ethernet0/0
O IA    10.0.0.4 [110/20] via 10.0.0.9, 00:01:53, Ethernet0/0

You can check virtual-link's status:

R3#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 2.2.2.2 is up
  Run as demand circuit
  DoNotAge LSA allowed.
  Transit area 1, via interface Ethernet0/1, Cost of using 10
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:05
    Adjacency State FULL (Hello suppressed)
    Index 1/3, retransmission queue length 0, number of retransmission 0
    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
    Last retransmission scan length is 0, maximum is 0
    Last retransmission scan time is 0 msec, maximum is 0 msec

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