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VTP configuration


I have two 6509 core switches and those are VTP servers.

Access switches 3550 and working in stacks, now I haven't configured VTP information on some access switches- info like VTP doamin name and mode.

But still those are getting VLAN info and SHOW VTP STATUS as VTP server (default). switch is working and it has accepted higher vtp conf version, as i think without configuring vtp domain name it should not accept any configuration, how do it gets vtp domain name? How is this possible?

On those access switches configured with VTP info are Ok they are showing SHOW VTP STATUS as client.

What functionality diffrence it will make if i give VTP mode and domain name on access switches rather than not providing the same? Any vlan addition on access switch, will it get carried to core switches - from client to server?

One more thing, is there any command or utility in cisco to protect important ip addresses like ip of core switches and routers getting conflict with others in large network, means considering manual mistakes?



Re: VTP configuration


if you take a new switch from the box and coonect it to your network, it's using the default VTP values: VTP mode server, no VTP domain configured.

So it's listening to VTP frames and when the first frame comes, the switch accepts VTP domain name from it, updates it's VLAN database and works as VTP server.

So if you want to protect the new switches from accepting VTP domain from VTP frames passing by, either configure them as VTP transparent or use a VTP password in your network.

See details in

To your last question:

Do you mean to configure ARP entries on routers manually?



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