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Webcast-Catalyst9k
New Member

vtp client operation

I'm looking for the normal operation of switches config. as vtp clients.

Vtp documentation tells me that vtp clients don't remember vlans. What does that mean?

Having some 2950s in client mode and to me it looks like it store the config. in vlan.dat. After I reconnect a client from the reset of the network and reboot , it has all the vlan config. when it up again. Is this normal?

Should the vtp Configuration Revision number be 0 after reload of a client?

Should the vtp Configuration Revision number be 0 after changing it from client to server (or from server to client)?

2 REPLIES
New Member

Re: vtp client operation

Switches generally store the vlan configuration in nvram. I am not sure, but setting the rev number to 0 would force the switch to evaluate any configuration updates from vtp servers. That is most likely by design to ensure accuracy in the vtp domain.

New Member

Re: vtp client operation

Vlan information is stored in the vlan.dat file and the safest way to put a vtp client into the network is just to delete the vlan.dat file and reload. A client will retain vlan information after reboot and will even force new vlans to be added to the VTP servers if it has a higher revision number.

One particularly nasty set of circumstances can arise when you have multiple VTP domains and devices are relocated. If you install the switch in a different VTP domain without deleting the vlan.dat file and the rev is higher, then change the vtp domain, all the vlans from the first domain are updated to the

second. At best this will rename a few vlans, at worst it can delete the lot or exceed the number of vlans supported and kick all the clients into transparent mode. With VTP around you'll never get complacent about installing a simple edge device again.

Cisco do explain this in roundabout terms:-

http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52.shtml#vtp_ts_rec_ins

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