VTP v3 and pruning

[agapitca19]

Hi,

We will be upgrading our distribution and access switches. Distribution switches are running in vtp server mode, while access switches are in mix of vtp client and transparent.

I am for setting all new switches to transparent mode and have manual pruning,as preventing accidental or intentional vlan database deletion outweighs having the convenience of dynamic vlan propagation. but my manager still wants to have the latter. so i made some research and found out about vtp v3 that has enhanced security feature for vlan deletion.

I want to know your opinion on my plan to implement vtp v3 when the new switches especially the distribution switches(it will be installed first while old access switches are still connected to them and get replaced) are introduced to our network. 

1. Install the new distribution switches with vtp v3, different vtp domain, password, and as primary server. The vlans on the new distribution switches should not propagate to the old access switches as they won't agree to the new vtp configs(domain,password,version?) of the distribution switches, right? 

2. As we install the new access switches gradually, they will have the same vtp configs as the new distribution switches except as clients.

3. I also want to enable vtp pruning on the new distribution switches when they get installed. After completing the switch upgrade, let's say we have 20 access switches and one day vlan 2 that was pruned needs to be not pruned only on 10 switches. Is it automatic to reverse the pruning for vlan 2 as soon as ports are assigned to vlan 2 to those 10 access switches?

Thanks!

[Georg Pauwen]

Hello,

1. Looks good. Obviously, make sure that when you add a client switch, the revision number of that switch is lower than that of the other switches.

2. Ditto. VTP configs will be propagated to the client switches.

3. With pruning enabled, adding a port to a VLAN will reverse pruning on the respective switch(es) and trunk(s). Keep in mind that even with VTP version 3, extended VLANs are still not pruned (>1005).

[agapitca19]

1. But am i right? that the vlans on the new distribution switches with vtp v3 configs on it won't propagate to the old switches(until the new switches get installed and have the same vtp v3 configs except as clients).

About vtp config revision number.from what i understand in vtp v3,it doesn't matter anymore coz if other switches have received a vtp frame with a higher revision number from a switch that is not registered as vtp primary server,the other switches won't update their vlan database.

3. We won't be using extended vlans.is there a way to prune them anyway?

Thanks.

[Georg Pauwen]

Hello,

you are right, in VTP 3, a new switch added to the network cannot update the domain even if it has a higher configuration revision number. I didn't know that !

On point 1: yes, you are right as well. VTP domain and password configured on the new switches will make sure that the old switches sync with the new ones.

On point 3: even in VTP 3, extended VLANs cannot be pruned. I am trying to find the reason why, actually...