Is there an exception to the rule "vlans cannot be created or modified" in client mode in vtp

[bhatiav04]

Is there an exception to the rule "vlans cannot be created or modified" in client mode in vtp

[Sarbjit-2014]

Hi,

No exception its the main reason to be in Client mode, Try Server or Transparent mode to create/modify VLANs.

Kind Regards.

[bhatiav04]

Hello Sarbjit,

Thanks for the response. I was asked about this in an interview question. And I replied the same. but he asked me it is possible and gave me as a homework. :) so was curious to know.

Regards

Vipul

[InayathUlla Sharieff]

Vipul,

Not sure what your interviewer was expecting as an answer. But yes your understanding is perfectly correct that you cannot create/modify/delete the vlans from client mode as it would through you the error saying: " VTP vlan configuration ont allowed when the device is in CLIENT mode.".

The only difference I can think of:  As a _user_ in VTP client mode you have restrictions on_what you can do_ (create,delete,modify) to the vlan.dat file whereas in Server mode you(the user) have none of those restrictions. But from the _switches'_ own perspective it doesn't make the distinction between the two modes. In other words the switch is not aware of the mode the other switches are in.

A switch would not advertise to another switch like "hey I am a client/server"  but will advertise "hey this is my revision number" and the other switch will then compare to it's own. The one with the highest revision number will be the one who gets the privelege to 'sync' its vlan.dat to the other switch.

HTH

[glen.grant]

  The only way it could change anything in client mode is if you stick a new switch into the vtp domain  (in client mode) with a higher vtp revision , if you do that then everything in the domain will change to the vlan setup on the switch that was inserted into the network.  Maybe thats what he was going for .

[Joseph W. Doherty]

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Posting

Or a possible variation (i.e. not needing a new switch), shut down trunk link(s), change VTP mode to server, change VLAN information, change VTP mode to client, then lastly, unshut the trunk link(s).

All rather involved, but it would permit a "client" mode switch to change VLAN information used by other switches.