Solved: Virtual Link problem in OSPF

Sanjay Shaw · ‎08-09-2011

Hi,

I am not able to connect a virtaul link to the backbone over a gns3. Please suggest if anything need to be changed. Every router are forming the adjacency but still not able to reach backbone Area0. Topology attached.

R1

interface Loopback0

ip address 1.1.1.1 255.255.255.255

!

interface Serial0/0

ip address 192.168.1.1 255.255.255.252

serial restart-delay 0

!

interface Serial0/1

ip address 172.16.1.1 255.255.255.252

serial restart-delay 0

!

interface Serial0/2

ip address 172.16.2.1 255.255.255.252

!

router ospf 1

log-adjacency-changes

area 1 virtual-link 2.2.2.2

network 1.1.1.1 0.0.0.0 area 0

network 172.16.1.0 0.0.0.3 area 0

network 192.168.1.0 0.0.0.3 area 1

**************

R2

R2#

interface Loopback0

ip address 2.2.2.2 255.255.255.0

!

interface Serial0/0

ip address 192.168.1.2 255.255.255.252

serial restart-delay 0

!

interface Ethernet1/0

ip address 10.1.2.2 255.255.255.0

full-duplex

!

router ospf 1

log-adjacency-changes

area 1 virtual-link 1.1.1.1

network 2.2.2.2 0.0.0.0 area 2

network 10.1.2.0 0.0.0.255 area 2

network 192.168.1.0 0.0.0.3 area 1

*****

R3

interface Loopback0

ip address 3.3.3.3 255.255.255.255

!

interface Serial0/0

ip address 172.16.1.2 255.255.255.252

serial restart-delay 0

!

interface Serial0/1

ip address 172.16.3.1 255.255.255.252

serial restart-delay 0

!

router ospf 1

log-adjacency-changes

network 3.3.3.3 0.0.0.0 area 0

network 172.16.1.0 0.0.0.3 area 0

network 172.16.3.0 0.0.0.3 area 0

******

Waiting for your suggestion. Thanks in advance.

SunilKhanna · ‎08-09-2011

Which is Area 1 and Area 2.

Pls refer here "OSPF Virtual Link"

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9ee.shtml

Regards,

Sunil

Pls rate the post if you find the content useful.

Regards, Sunil Khanna

View solution in original post

Peter Paluch · ‎08-09-2011

Hello,

Please verify using the show ip ospf virtual-link whether the virtual link has come up. Quickly skimming over your configuration, there does not seem to be any obvious configuration problem but it is possible that your router IDs do not correspond to those used in the virtual link configuration. Use the show ip ospf to verify the RID on R1 and R2, and I also suggest fixing the RIDs using the OSPF configuration command router-id

Best regards,

Peter

Sanjay Shaw · ‎08-09-2011

Hi Peter,

Thanks for ur interest to give a sugesstion, please have a look i.e., RID are correctly set over VL.

R1#sh ip ospf

Routing Process "ospf 1" with ID 1.1.1.1

Start time: 00:00:11.948, Time elapsed: 01:49:03.548

Supports only single TOS(TOS0) routes

Supports opaque LSA

Supports Link-local Signaling (LLS)

Supports area transit capability

It is an area border router

Router is not originating router-LSAs with maximum metric

Initial SPF schedule delay 5000 msecs

Minimum hold time between two consecutive SPFs 10000 msecs

Maximum wait time between two consecutive SPFs 10000 msecs

Incremental-SPF disabled

Minimum LSA interval 5 secs

Minimum LSA arrival 1000 msecs

LSA group pacing timer 240 secs

Interface flood pacing timer 33 msecs

Retransmission pacing timer 66 msecs

Number of external LSA 0. Checksum Sum 0x000000

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 2. 2 normal 0 stub 0 nssa

Number of areas transit capable is 1

External flood list length 0

Area BACKBONE(0)

Number of interfaces in this area is 3 (1 loopback)

Area has no authentication

SPF algorithm last executed 01:01:42.564 ago

SPF algorithm executed 3 times

Area ranges are

Number of LSA 8. Checksum Sum 0x05EBC8

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 4

Flood list length 0

Area 1

Number of interfaces in this area is 1

This area has transit capability: Virtual Link Endpoint

Area has no authentication

SPF algorithm last executed 01:01:42.572 ago

SPF algorithm executed 4 times

Area ranges are

Number of LSA 8. Checksum Sum 0x05569F

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

R1#sh ip ospf n

Neighbor ID Pri State Dead Time Address Interface

3.3.3.3 0 FULL/ - 00:00:33 172.16.1.2 Serial0/1

2.2.2.2 0 FULL/ - - 192.168.1.2 OSPF_VL0

2.2.2.2 0 FULL/ - 00:00:30 192.168.1.2 Serial0/0

**************

R2#sh ip ospf

Routing Process "ospf 1" with ID 2.2.2.2

Start time: 00:00:13.508, Time elapsed: 02:02:52.380

Supports only single TOS(TOS0) routes

Supports opaque LSA

Supports Link-local Signaling (LLS)

Supports area transit capability

It is an area border router

Router is not originating router-LSAs with maximum metric

Initial SPF schedule delay 5000 msecs

Minimum hold time between two consecutive SPFs 10000 msecs

Maximum wait time between two consecutive SPFs 10000 msecs

Incremental-SPF disabled

Minimum LSA interval 5 secs

Minimum LSA arrival 1000 msecs

LSA group pacing timer 240 secs

Interface flood pacing timer 33 msecs

Retransmission pacing timer 66 msecs

Number of external LSA 0. Checksum Sum 0x000000

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 3. 3 normal 0 stub 0 nssa

Number of areas transit capable is 1

R2#sh ip ospf n

Neighbor ID Pri State Dead Time Address Interface

1.1.1.1 0 FULL/ - - 192.168.1.1 OSPF_VL0

1.1.1.1 0 FULL/ - 00:00:32 192.168.1.1 Serial0/0

Please suggest still the RID needs to be hardcoded

Jon Marshall · ‎08-09-2011

What does "sh ip ospf virtual-links" show ?

Jon

Peter Paluch · ‎08-09-2011

Jon, Sanjay,

According to the show ip ospf neighbor output displayed by Sanjay, the OSPF adjacency has been fully established over the virtual link (see the OSPF_VL0 entry in the output) so I would say the virtual link itself should work correctly. The RIDs do not need to be hardcoded under these circumstances, although having them hardcoded is a best practice.

Sanjay, can you please be very specific about the issue you are trying to solve, i.e. show us exactly the routing table that is missing some route, etc.? So far your description of the problem has been somewhat vague - that "Every router are forming the adjacency but still not able to reach backbone Area0." Can you make that more precise?

Thank you!

Best regards,

Peter

Sanjay Shaw · ‎08-09-2011

Hi All,

Thanks to u all for giving me the update. Please find after changing the area Id in all the router things got resolved now my virtual Links are working.

R2

router ospf 1

log-adjacency-changes

area 1 virtual-link 3.3.3.3

network 2.2.2.2 0.0.0.0 area 2

network 10.1.2.0 0.0.0.255 area 2

network 192.168.1.0 0.0.0.3 area 1

R2#sh ip ospf n

Neighbor ID Pri State Dead Time Address Interface

3.3.3.3 0 FULL/ - - 172.16.1.2 OSPF_VL1

1.1.1.1 0 FULL/ - 00:00:36 192.168.1.1 Serial0/0

************

R1

router ospf 1

log-adjacency-changes

network 172.16.1.0 0.0.0.3 area 1

network 192.168.1.0 0.0.0.3 area 1

R1#sh ip ospf n

Neighbor ID Pri State Dead Time Address Interface

3.3.3.3 0 FULL/ - 00:00:35 172.16.1.2 Serial0/1

2.2.2.2 0 FULL/ - 00:00:38 192.168.1.2 Serial0/0

*****************

R3#sh run | b network

network 3.3.3.3 0.0.0.0 area 0

network 172.16.1.0 0.0.0.3 area 1

network 172.16.3.0 0.0.0.3 area 0

R3#sh ip ospf n

Neighbor ID Pri State Dead Time Address Interface

2.2.2.2 0 FULL/ - - 192.168.1.2 OSPF_VL3

1.1.1.1 0 FULL/ - 00:00:37 172.16.1.1 Serial0/0

***********************

Thanks 1 more times u all.

SunilKhanna · ‎08-09-2011

Which is Area 1 and Area 2.

Pls refer here "OSPF Virtual Link"

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9ee.shtml

Regards,

Sunil

Pls rate the post if you find the content useful.

Regards, Sunil Khanna