The primary purpose for VTP is to propagate VLAN information configured on one switch to all the remaining switches in the network. This allows for central control. Even when using VTP, only vlan information (not ports assigned to the VLAN on one switch) is propagated across all the other switches, one must still go and specify which ports will be part of a VLAN on each switch.

So ,if we must go and add ports on each switch to respective VLANs, then why use VTP? it avoids VLAN misconfigurations such as wrong VLAN names,types etc.

HTH

Lejoe

Using VTP also makes life easier when configuring core and distribution switches with many trunks, any new VLAN's are propagated between all the core and distribution switches in the VTP domain.

Essentially VTP reduces administration in a switched network. When you configure a new VLAN on the designated VTP server, the VLAN is distributed through all switches in the

domain.

As you mentioned this reduces the overall need for configuring the same VLAN everywhere. However, there are situations where broadcast will be flooded in a VLAN, and if the VLAN is allowed across all trunk ports, then so will the broadcast.

A feature of VTP is VTP pruning which will prune this traffic if there are no members assigned to this VLAN at edge for example. It will only be flooded to switches where the switchports with active port member in that given VLAN.

In your case your are effectively creating and duplicating all the VLANs across your network, which is effectively the same as the VTP Transparent mode, it will be necessary to manually add or clear unwanted VLANs from your trunk ports.

I find that Transparent mode gives you more control over where you extend your broadcast domains. In such sitations you are specifically required to configure the vlan on switches.

Therefore transparent mode is better suited to static enviroments where you are not constantly moving ports between vlans across access switches.

Hope this helps.

Allan.

Pls rate helpful posts.

Things are not always so simple, there are cases where you have transit switches that doesn't host ports for some specific vlans, since you need to create vlans through all the path from core to access in order for the traffic to flow, you need vtp or manually create vlans on transit switches.

Bye,

Tosh.