Packet Tracer OSPF Virtual Link, Problem with Area, route table

[Sarius]

Hi,

I have a problem with my network in packet tracer. I tried to build a ospf network with 4 areas. One of them, area 2, isnt directly connected to the area 0/Backbone. So I use the virtual-link to connect this area 2 with area 0. But every time I start the file I got a different result. In the most of the time I have two different cases.

In the first case the virtual-link got the status full and area 2 knows the network from area 0 but area 2 dont know the networks from area 1. The weird thing is that, area 2 know the backbone but not area 1, but area 1 has the networks from area 2. So I can make a ping from area 1 to area 2 and I can follow the packet till area 2. In area 2 the packet is dropping because area 2 dont know the networks from area 1.

In the second case all works fine and I can ping from every device and area to other devices and areas.

Im really confused about the situation that I got different results from one file. I started a test and open the same file eleven times in row. I closed every time without to save. And this was the results:

1. case 1

2. case 1

3. case 1

4. case 1

5. case 2

6. case 1

7. case 1

8. case 1

9. case 1

10. case 2

11. case 1

So the problems again:

   - two different results from the same file

   - area 2 see area 0 but didnt see area 1 although virtual-links are full and area 1 see area 2

Can you help me regarding this problem? Is that a known issue by ospf and virtual-links in packet tracer?

I attached the file (ospf-lab in zip) and pictures about the topology and cases.

Regards

Sarius

edit: I have imported the configurations and not typed them out individually on the router. I had adjusted the configurations beforehand. (if this is important)

[Giuseppe Larosa]

Hello @Sarius 

I would say you are hitting an issue with packet tracer as most of the times it works.

the transit area 3 must be a standard area ( it cannot be any form of stub or NSSA)

Virtual link must be configured between ABR nodes ABR (3,2) and ABR (3,0) using their respective OSPF Router IDs

Hope to help

Giuseppe

[Martin L]

I don't know if packet tracer supports ospf virtual-links (and other advanced features).  Probably not as packet tracer is just IOS software simulator, not real IOS nor behave as one. Check PT under Help menu for list of supporting features and behavior of them.

For real routing you can use GNS3 which requires real IOS; I would recommend the IOS 15.x from 7200s router - only IOS 15 version supported in GNS3.  Other IOS supported by GNS3 are version 12.4 from 2600s, 3660s, 3745s routers.

Regards, ML
**Please Rate All Helpful Responses **

[Georg Pauwen]

Hello,

I think it works as designed, it just takes a long time for the network to converge. If you open the file (which I amended a bit by adding loopbacks for the router IDs), it takes a good 2 minutes before all networks are visible on each router.

[Sarius]

Hi,

I have forgotten to write that after every start of a file I play the first ten minutes forward. Unfortunately I have the same issue with your file. I can see that you have for every router add a router-id like you have written. But in my case it changes nothing. I got still the problem "case 1" (area 2 didnt see area 1, but area 1 see area 2). Did your file work on your device if open it two times in row? I add a picture with the problem regarding your file (network 192.168. 10/11/13/15 .0 is missing).

[Georg Pauwen · Accepted solution]

Hello,

I did virtual links in Packet Tracer in the past. I think the problem in your topology is that there are too many (9) routers. Try and use something like 5 at most:

R1(Area0) - R2 (Area0/Area1 ABR) - R3 (Area1) - R4 (Area1/Area2 ABR) - R5 (Area2)

The configuration you are using is completely valid, but somehow PT cannot handle the complexity, which leads to unpredictable results.

[Sarius]

Okey, I did it like you said. I built a network with 5 routers and try again to opening the file ten times in a row. And Surprising the file works fine! Every single opening file got all networks and every device/area see the others.

So it seems like you said, that the packet tracer got a problem with bigger complexer networks.

If you interested and want to tested too I attached the file and one picture from the topology.

Thanks for your comments!

[Georg Pauwen]

Hello,

it works over here as well. Good to know. That means your configs are perfectly ok.

PT is a very good tool, but it has some limitations...