Hello Philip
That’s interesting behaviour… The transparent switch should relay the VTP updates to the client switch without any problems. I labbed it up and tried it out and I find that the client switch was able to obtain the updates. However, what I suspect happened is the following:
VTP, when it is configured on switches, does not send out information periodically. It will only send updates when the state changes. (when a VLAN is added or subtracted, or when you change a configuration parameter of VTP). For example, if you configure VTP first and then physically connect two switches together over a trunk, VTP will not send an update from the server to the client. The update will only be sent if there is a change. So, in order for the client to get VTP information, a change must take place. You must add a VLAN. I suspect that this is what you did:
- you first configured the three switches with VTP, one as a server, one as transparent, and one as a client.
- you then connected the switches together and found that no VTP updates were being sent from server to client (this is normal behaviour).
- you then changed the mode of the transparent switch which initiated VTP communication between all three switches. This caused the server to send out VTP updates, and both clients got updated.
- you then made the middle switch transparent, and VTP functioned normally.
If you had connected the switches first and then configured VTP, then it would have functioned from the beginning. Does that make sense?
I hope this has been helpful!
Laz