Saturday, August 22, 2015

OSPF - Virtual link




Case 1 Virtual-link between for Area 3 with Transit area 4

R6

R6#sh ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
55.5.5.5          1   FULL/DR         00:00:36    56.0.0.5        FastEthernet0/1
R6#


R6#sh ip route ospf

      5.0.0.0/32 is subnetted, 1 subnets
O        5.5.5.5 [110/11] via 56.0.0.5, 00:00:56, FastEthernet0/1

No route from other Areas


R6#sh ip ospf border-routers



            OSPF Router with ID (66.6.6.6) (Process ID 10)


                Base Topology (MTID 0)


No Border-routers available

R5 

R5#sh ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
66.6.6.6          1   FULL/BDR        00:00:34    56.0.0.6        FastEthernet0/1
2.2.2.2           1   FULL/BDR        00:00:39    25.0.0.2        FastEthernet0/0



R5#   sh ip ospf border-routers

            OSPF Router with ID (55.5.5.5) (Process ID 10)

i 2.2.2.2 [10] via 25.0.0.2, FastEthernet0/0, ABR, Area 4, SPF 3

*****************8
***************************
Gateway of last resort is not set

      6.0.0.0/32 is subnetted, 1 subnets
O        6.6.6.6 [110/11] via 56.0.0.6, 00:14:31, FastEthernet0/1
      9.0.0.0/32 is subnetted, 1 subnets
O IA     9.9.9.9 [110/10011] via 25.0.0.2, 00:12:25, FastEthernet0/0
      13.0.0.0/24 is subnetted, 1 subnets
O IA     13.0.0.0 [110/30] via 25.0.0.2, 00:12:25, FastEthernet0/0
      16.0.0.0/24 is subnetted, 1 subnets
O        16.0.0.0 [110/20] via 56.0.0.6, 00:14:31, FastEthernet0/1
      23.0.0.0/24 is subnetted, 1 subnets
O IA     23.0.0.0 [110/20] via 25.0.0.2, 00:12:25, FastEthernet0/0
      34.0.0.0/24 is subnetted, 1 subnets
O IA     34.0.0.0 [110/21] via 25.0.0.2, 00:12:25, FastEthernet0/0
      102.0.0.0/24 is subnetted, 1 subnets
O IA     102.1.0.0 [110/11] via 25.0.0.2, 00:12:25, FastEthernet0/0
      172.16.0.0/32 is subnetted, 3 subnets
O IA     172.16.0.2 [110/10] via 25.0.0.2, 00:12:25, FastEthernet0/0
O IA     172.16.0.4 [110/10010] via 25.0.0.2, 00:12:25, FastEthernet0/0
O IA     172.16.0.9 [110/10010] via 25.0.0.2, 00:12:25, FastEthernet0/0


Hear in this example R6 does not have routes from another AREA and dos not have any border routers.because this area is not attached to AREA 0

to resolve this we make virtual link between AREA 3 and AREA 0 via AREA 4
R2
R2#sh ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
39.1.4.1          1   FULL/DR         00:00:35    23.0.0.3        FastEthernet0/1
44.4.4.4          0   FULL/  -        00:01:50    172.16.0.4      Tunnel0
172.16.0.9        0   FULL/  -        00:01:50    172.16.0.9      Tunnel0
55.5.5.5          1   FULL/DR         00:00:30    25.0.0.5        FastEthernet0/0

R2(config)#router ospf 10
R2(config-router)#area 4 virtual-link 55.5.5.5

R5

R5#sh ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
66.6.6.6          1   FULL/BDR        00:00:34    56.0.0.6        FastEthernet0/1
2.2.2.2           1   FULL/BDR        00:00:39    25.0.0.2        FastEthernet0/0

R5(config)#router  ospf 10
R5(config-router)#area 4 virtual-link 2.2.2.2

R5#sh ip ospf  nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           0   FULL/  -           -        25.0.0.2        OSPF_VL0
66.6.6.6          1   FULL/BDR        00:00:37    56.0.0.6        FastEthernet0/1
2.2.2.2           1   FULL/BDR        00:00:33    25.0.0.2        FastEthernet0/0
R5#


R5#sh 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 4, via interface FastEthernet0/0
 Topology-MTID    Cost    Disabled     Shutdown      Topology Name
        0           10        no          no            Base
  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 1/2, 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

Now in R6

R6#sh ip ospf border-routers

            OSPF Router with ID (66.6.6.6) (Process ID 10)


                Base Topology (MTID 0)

i 55.5.5.5 [10] via 56.0.0.5, FastEthernet0/1, ABR, Area 3, SPF 18
R6

Sh Ip route ospf
      5.0.0.0/32 is subnetted, 1 subnets
O        5.5.5.5 [110/11] via 56.0.0.5, 00:22:05, FastEthernet0/1
      9.0.0.0/32 is subnetted, 1 subnets
O IA     9.9.9.9 [110/10021] via 56.0.0.5, 00:06:26, FastEthernet0/1
      13.0.0.0/24 is subnetted, 1 subnets
O IA     13.0.0.0 [110/40] via 56.0.0.5, 00:06:26, FastEthernet0/1
      15.0.0.0/24 is subnetted, 1 subnets
O IA     15.0.0.0 [110/50] via 56.0.0.5, 00:06:26, FastEthernet0/1
      23.0.0.0/24 is subnetted, 1 subnets
O IA     23.0.0.0 [110/30] via 56.0.0.5, 00:06:26, FastEthernet0/1
      25.0.0.0/24 is subnetted, 1 subnets
O IA     25.0.0.0 [110/20] via 56.0.0.5, 00:06:41, FastEthernet0/1
      34.0.0.0/24 is subnetted, 1 subnets
O IA     34.0.0.0 [110/31] via 56.0.0.5, 00:06:26, FastEthernet0/1
      55.0.0.0/32 is subnetted, 1 subnets
O IA     55.5.5.5 [110/11] via 56.0.0.5, 00:06:41, FastEthernet0/1
      102.0.0.0/24 is subnetted, 1 subnets
O IA     102.1.0.0 [110/21] via 56.0.0.5, 00:06:26, FastEthernet0/1
      172.16.0.0/32 is subnetted, 3 subnets
O IA     172.16.0.2 [110/20] via 56.0.0.5, 00:06:26, FastEthernet0/1
O IA     172.16.0.4 [110/31] via 56.0.0.5, 00:06:26, FastEthernet0/1
O IA     172.16.0.9 [110/10020] via 56.0.0.5, 00:06:26, FastEthernet0/1
R6#

R6#trace 9.9.9.9
Type escape sequence to abort.
Tracing the route to 9.9.9.9
VRF info: (vrf in name/id, vrf out name/id)
  1 56.0.0.5 152 msec 212 msec 156 msec  R5
  2 25.0.0.2 268 msec 264 msec 160 msec  R2
  3 172.16.0.9 716 msec 428 msec 444 msec
R6#

Authentication

R2

router ospf 10
 auto-cost reference-bandwidth 1000
 area 0 authentication
 area 4 virtual-link 55.5.5.5 authentication-key cisco
 or
router ospf 10
 auto-cost reference-bandwidth 1000
area 4 virtual-link 55.5.5.5 authentication authentication-key cisco


R5
router ospf 10
 auto-cost reference-bandwidth 1000
 area 0 authentication
 area 4 virtual-link 2.2.2.2 authentication-key cisco
or

router ospf 10
area 4 virtual-link 2.2.2.2  authentication   authentication-key cisco


Logs

R5#sh ip ospf int
OSPF_VL0 is up, line protocol is up
  Internet Address 25.0.0.5/24, Area 0, Attached via Not Attached
  Process ID 10, Router ID 55.5.5.5, Network Type VIRTUAL_LINK, Cost: 10
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           10        no          no            Base
::::::::::
Transmit Delay is 1 sec, State POINT_TO_POINT
:::::::::;
 Simple password authentication enabled



%OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on OSPF_VL0 from FULL to DOWN, Neighbor Down: Interface down or detached





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