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Community Member

OSPF Virtual link design issue

Hi all,

I have  the Lab setup  like below

R1  area 0

R2 is ABR area 0 and 20

R3 is connected to R2 and R4 in Area 20 only.

R3 is an ASBR *****************************************************************************************************

R4 is connected to R3 and R5  Area  20 and area 12 only.

R5 is Area 12 only connected to R4.

R5 is an ASBR *******************************************************************************************************

I have created Virtual link between R2 and R4  but link on both ends shows down.

Thanks

Message was edited by: mahesh parmar

Everyone's tags (5)
4 ACCEPTED SOLUTIONS

Accepted Solutions
VIP Super Bronze

OSPF Virtual link design issue

So, here it is. try a link between r5 and r2.  You virtual link would transit through area 20

VIP Super Bronze

OSPF Virtual link design issue

Community Member

OSPF Virtual link design issue

Hi Mahesh,

The purpose of defining a virtual link is to "connect" an area to Area 0. If I understand correctly from your post, you have Area 12 which is not directly connected to Area 0. In this case, you have to make a virtual link between one of the ABRs of Area 0 to one of the ABRs of Area 12.

In the above case, you have to make a virtual link between R2 and R3 and it will look like that:

R2:

router ospf 1

router-id 2.2.2.2

log-adjacency-changes

area 20 virtual-link 3.3.3.3

network 10.10.12.2 0.0.0.0 area 0

network 10.10.23.2 0.0.0.0 area 20

R2#sh ip os int b

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

VL0          1     0               10.10.23.2/24      10    P2P   1/1

Fa0/0        1     0               10.10.12.2/24      10    DR    1/1

Fa0/1        1     20              10.10.23.2/24      10    BDR   1/1

R3:

router ospf 1

router-id 3.3.3.3

log-adjacency-changes

area 20 virtual-link 2.2.2.2

network 10.10.23.3 0.0.0.0 area 20

network 10.10.34.3 0.0.0.0 area 12

R3#sh ip os int b

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

VL0          1     0               10.10.23.3/24      10    P2P   1/1

Fa0/0        1     12              10.10.34.3/24      10    BDR   1/1

Fa0/1        1     20              10.10.23.3/24      10    DR    1/1

Now, R3 virtually has an interface in Area 0, even though it is not connected to Area 0.

Hope this helps.

Community Member

OSPF Virtual link design issue

Hey Mahesh18,

Based on the information you've provided above...below I've drawn your OSPF design (dashed line is the virtual link).

If my drawing is accurate then the following steps will connect area 12 to area 0 and get you on your way.  Note:  This assumes all interfaces are up and reachable.

1. On R4 - under the OSPF process configure the following

          -  area 20 virtual-link [R2 router-id]

2. On R2 - uncer the OSPF process configure the following

          - area 20 virtual-link [R4 router-id]

That's all there is...  Hope this helps!

20 REPLIES

OSPF Virtual link design issue

Mahesh,

umm where you setting up the virtual link seems to be ok. umm cant tell unless we see some more information. hows the ip addressing and all . Are the devices able to see each other. I mean R2 and R3.

Maybe this link will give some information on virtual links

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

can you please post a diagram so that its more clear how its all connected.

Regards, Kishore

Community Member

OSPF Virtual link design issue

Hi Kishore,

Unfortunately i have no diagram yet.

R2 can only see R3s interface which are directly connected.

R2 is unable to see the interface IP of R3 which connects to R4.

Thanks

MAhesh

VIP Super Bronze

OSPF Virtual link design issue

Hi Mahesh,

Is this your setup?

If yes, you need a virtual link between r5 and r2

Community Member

OSPF Virtual link design issue

Hi Reza,

My setup is like this

R1 is in Area 0 and has physical connection to R2.

R2 has 1 interface in area 0 and 1 interface in area 20.

R3 has 2 physical interfaces and they are connected to R2 and R4.

R3 is in area 20 only.

R4 has 1 interface in area 20 and 1 interface in area 12.

R5 has physical connection to R4 .

R5 is in area 12 only.

I hope this helps

Thanks

MAhesh

Community Member

OSPF Virtual link design issue

Let me try  link betwwen r5 and r2

thanks

VIP Super Bronze

OSPF Virtual link design issue

So, here it is. try a link between r5 and r2.  You virtual link would transit through area 20

Community Member

OSPF Virtual link design issue

Hi Reza,

Thanks for making nice diagram.

I tried between R2 and R5 using area 20 still down.

Just let you know R3 and R5 are ASBR *******************

i am not sure that will have any effect on virtual link or not?

thanks

MAhesh

Community Member

OSPF Virtual link design issue

Hi Reza,

I created Virtual link between R5 and R2 using area 20 still it is down down

VIP Super Bronze

OSPF Virtual link design issue

Community Member

OSPF Virtual link design issue

Hi Reza,

I read the document and now tried virtual  link between R2 and R2 area 20 still down down

Thanks

MAhesh

VIP Super Bronze

OSPF Virtual link design issue

Hi Mahesh,

Do you mean r2 and r5?

r3 and r4 are already connected to area 0, so you would need a virtual link from r5 to r2 transiting r4.

HTH

Community Member

OSPF Virtual link design issue

Hi Reza,

As per your 2nd diagram i tried r 2 and r5 then r2 and r4 still no luck

thanks

mahesh

Community Member

OSPF Virtual link design issue

Dear Mahesh,

You havent mentioned Area 2 in your topology description, whereas your " shows ip ospf" shows one of your interfaces in Area 2.

Community Member

OSPF Virtual link design issue

Hi Daud,

  Area BACKBONE(0) (Inactive)

        Number of interfaces in this area is 2 (1 loopback) *****************************

This tells number of interaces in this area is 2 not area number if i am correct.

Thanks

MAhesh

Community Member

OSPF Virtual link design issue

Hi Mahesh,

The purpose of defining a virtual link is to "connect" an area to Area 0. If I understand correctly from your post, you have Area 12 which is not directly connected to Area 0. In this case, you have to make a virtual link between one of the ABRs of Area 0 to one of the ABRs of Area 12.

In the above case, you have to make a virtual link between R2 and R3 and it will look like that:

R2:

router ospf 1

router-id 2.2.2.2

log-adjacency-changes

area 20 virtual-link 3.3.3.3

network 10.10.12.2 0.0.0.0 area 0

network 10.10.23.2 0.0.0.0 area 20

R2#sh ip os int b

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

VL0          1     0               10.10.23.2/24      10    P2P   1/1

Fa0/0        1     0               10.10.12.2/24      10    DR    1/1

Fa0/1        1     20              10.10.23.2/24      10    BDR   1/1

R3:

router ospf 1

router-id 3.3.3.3

log-adjacency-changes

area 20 virtual-link 2.2.2.2

network 10.10.23.3 0.0.0.0 area 20

network 10.10.34.3 0.0.0.0 area 12

R3#sh ip os int b

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

VL0          1     0               10.10.23.3/24      10    P2P   1/1

Fa0/0        1     12              10.10.34.3/24      10    BDR   1/1

Fa0/1        1     20              10.10.23.3/24      10    DR    1/1

Now, R3 virtually has an interface in Area 0, even though it is not connected to Area 0.

Hope this helps.

Community Member

OSPF Virtual link design issue

Hi,

Thanks for reply.

Right now R3 has both interfaces in area 20.

Should i change 1 interface of R3 from Area 20 to Area 12?

R4 has 1 interface in area 20 and it has connection to R5 which is area 12.

Thanks

MAhesh

Community Member

OSPF Virtual link design issue

Hey Mahesh18,

Based on the information you've provided above...below I've drawn your OSPF design (dashed line is the virtual link).

If my drawing is accurate then the following steps will connect area 12 to area 0 and get you on your way.  Note:  This assumes all interfaces are up and reachable.

1. On R4 - under the OSPF process configure the following

          -  area 20 virtual-link [R2 router-id]

2. On R2 - uncer the OSPF process configure the following

          - area 20 virtual-link [R4 router-id]

That's all there is...  Hope this helps!

Community Member

OSPF Virtual link design issue

Hi Everyone,

Issue is fixed Virtual link is up now between  R2 and R4,

Issue was nei relationship between r2 and r3 were 2way/Drother.

I removed ip ospf priority 0 from both r2 and r3 interfaces and  virtual link came up.

Many thanks to everyone for there help.

Regards

MAhesh

Hall of Fame Super Silver

OSPF Virtual link design issue

Hello Mahesh,

>> I removed ip ospf priority 0 from both r2 and r3 interfaces and  virtual link came up.

You have been kind to provide valuable feedback on this thread. This is another happy end

Best Regards

Giuseppe

Community Member

OSPF Virtual link design issue

Hi Giuseppe,

This forum is great place to learn.

Its always good to share the knowledge here  and provide feedbacks of issues which get resolved.

Still i am learning a lot from you guys.

Thanks

MAhesh

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