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Rick Morris
Frequent Contributor

Redundant Switch Set-up VLAN

I am in the process of building out a new set-up and have never done anything like this. I am trying to figure out how to set this up.

I am setting this up in a lab for testing before I roll it out to production.

My topology:

1 2950 - MDF/IDF for testing this is what I have to do.

2 3560's - external switches.

2950 - port fa0/23 to 3560-A port fa0/21

2950 - port fa0/24 to 3560-B port fa0/21

Is is possible to run VTP in any type of redunant configuration?

I am fairly familiar with vlan set-up and VTP but never set this topology up before and wondered what others have done.

If I create 3560-A as the VTP server and everything else as client what happens if I lose that switch or connection to that switch via the 2950, should I trunk the 2 3560's together via port channeling so I the 2950 has access to 3560-A by way of 3560-B?

I am not looking for the answer, unless someone wants to give it ;0)

I just need pointed in the right direction.




VTP is "fault tolerant," so if you had 1 VTP server and 2 VTP clients, and for whatever reason you lost your VTP server, the clients would retain their VLAN configurations. Once you configured a new VTP server to be in the same domain, same password etc. the clients would actually update the VTP server to reflect their configuration.

How this works is based entirely on the VTP revision number, within the same VTP domain, the highest revision number is always trusted to be the most current information, whether it is a client or server.

You can test this by "resetting" the revision number of your VTP server after simulating a failure.

Use "show vtp status" to view the revision number, create a few VLAN's and verify the revision number has incremented and populated to all switches.

Disconnect the VTP server fromt eh other switches to simulate a failure.

Reset the revision number by changing the VTP domain name to any other random name, create a few random VLAN's and remove some of the original ones, change the domain name back to match the other switches.

Do a show vtp status to verify the revision number is 0 (or at least lower than what your client switches have), and reconnect the VTP server to the VTP domain, wait a few seconds and you will see the revision number of the server change to match the clients and the client information will populate the VTP servers table.

Port channels are no different than any other links with the exception that you can have multiple physical links that act as one, it wouldn't protect you in the event of a power failure. But they are always a good design choice for any redundant configuration :)



Thanks Craig!

This helps. I believe I am over thinking this whole project I am on that I often forget the simple ins and outs.

This helps and makes perfect sense. I believe I am on the right path now.