What is a Virtual Link?

DerekAustin26

I've checked google got 1 source that is very vague, and i've checked Todd Lammle's CCNA book & Boson's CCNA book. I cannot get a good explanation of what it is in lamens terms. Can someone help me out please?

ColbyG

Virtual Links are related to OSPF. In OSPF every area has to touch Area 0 (the backbone). A Virtual Link allows one area to traverse another area to touch area 0. So:

(Area 0)---(Area 1)---(Area 2)

You would have a Virtual Link between Area 0 and Area 2 so Area 2 is touching Area 0. It's basically just a tunnel to Area 0 through another area.

I hope that makes sense.

Edit: Check out this link:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094aaa.shtml#virtuallinks

ColbyG

Also, I don't think you need to worry about Virtual Links at the CCNA level.

DerekAustin26

It's not for my CCNA, I got a new job at a NOC and one of their MAPS we use for monitoring WAN links has a Virtual Link going from Tulsa, OK to Lake Charles, LA. And I've never heard of a virtual link in my life until today.

Slowhand

DerekAustin26 wrote: »

It's not for my CCNA, I got a new job at a NOC and one of their MAPS we use for monitoring WAN links has a Virtual Link going from Tulsa, OK to Lake Charles, LA. And I've never heard of a virtual link in my life until today.

At this rate, you'll make not only a good CCNA candidate, but a good CCNP and even CCIE someday. The mindset, "I haven't seen this before, I should learn about it," is lacking all too much wherever I go.

jonfc3s

Virtual circuits,... also known as vitual links can also relate to Frame Relay.

Jon

billscott92787

I totally agree. It is good you seen something and then asked about it! You don't see these until you get to the CCNP, BSCI portion of the exam, specifically OSPF. I like you attitude, it will take you far! That is how I am as well, if I see something I don't know, I ask and learn it.

APA

ColbyNA wrote: »

Virtual Links are related to OSPF. In OSPF every area has to touch Area 0 (the backbone). A Virtual Link allows one area to traverse another area to touch area 0. So:

Spot on.... mainly used when dis-contiguous areas are in the topology with no direct adjacency to Area 0

However.....

Just like to add that it's not a recommended configuration and if a final solution means using virtual-links then the design isn't a final solution....

adds complexity to a topology......

DerekAustin - to find out whether the Map you are talking about is indeed a OSPF virtual link... If you have access to one of the routers login and execute the following 'show command.

show ip ospf virtual-links

BTW - I concur with Slowhand.... great use of initiative... I too am suffering from the wrath of NOC admins not worrying about the ins and outs of work assigned to them\or what the graphs are telling them....