Changing from VTP Server/Client to Transparent - Traffic impact

[UHansen1976]

Hi,

Quick question. I have couple of Cat6509's with Cat4948 attached, currently running a traditional VTP client/server enviroment, with the Cat6509's acting as servers. However, I would like to change it to Transparent VTP across all switches.

The thing is, that this is a first for me, I've never done this in a live production enviroment, only on test-equipment. So I have no actual knowledge on what to expect as far as traffic impact goes. I would think, that this could be done without any traffic disruption, although I expect to perform it during a maintenance window.

Has anyone tried this and if so, what was your experience as far as disruption goes? And are there any particular things one should be aware of as far as spanning-tree goes? I'd imagine, that upon verifying that the VTP configuration is consistent across the VTP domain, then start with the clients and then move on the servers.

Any thoughts, ideas or recommendations are greatly appreciated.

Thanks

/Ulrich

[Jon Marshall · Accepted solution]

There should not be any impact on traffic as VTP is only concerned with the vlan database stored on each switch. You do need to make sure that all VTP clients have the most up to date vlan database before switching to VTP transparent.

Having said that you should if possible, and it sounds like you are, do this in a scheduled maintenance window just in case.

Jon

[Peter Paluch · Accepted solution]

Ulrich,

I agree with Jon, and I like to add one thing to watch for: if you are running VTP Pruning, it would be best to deactivate it before converting your switches to Transparent mode. The VTP Pruning relies on switches mutually reporting which VLANs are/aren't used so they can by dynamically allowed or pruned off trunk links (to prevent broadcasts, multicasts and unknown unicasts to flood into parts of network where there is no valid recipient). While switches in VTP Transparent mode should pass VTP messages, there may be situations when they do not, and that could cause the VTP Pruning to assume there are no VLANs being used behind the Transparent switches, and prune all VLANs from the trunks towards the transparent switch, effectively blackholing your traffic. A simple no vtp pruning on any of your VTP Server switches would disable the pruning for the entire VTP domain.

Best regards,

Peter

[UHansen1976]

Thanks for the feedback, guys. Much appreciated

/Ulrich