1 Reply Latest reply: Aug 15, 2012 3:43 AM by Iain RSS

    VTP Clarification

    Dean

      I am confused with VTP. The books explain that VTP propagates VLAN information to make switch management esier, but how does this help with regards to which access ports on which switch belong to which VLAN?

         
        • 1. Re: VTP Clarification
          Iain

          Hi Dean, as this issue isn't related to the learning labs you might have been better posting in the CCNA user group or somewhere similar. Regardless, the answer is quite simple. VTP doesn't know what access ports on the switch belong to a VLAN, but it does make sure that the VLANs themselves are created where they're needed.

           

          For example, if you have 3 switches A, B and C and want a VLAN from Port 1 on A to Port 2 on C, without VTP you need to log into all 3 switches and type:

           

          conf t

          vlan 20

          name PC LAN

           

          and then on A and C configure your ports "switchport access vlan 20; switchport mode access". When you only have a few switches it's not such a big deal and so VTP doesn't seem very helpful. When you have 20 switches however and 100s of VLANs it becomes a little more complicated if you have to figure out exactly which switches you need to create the VLANs on for the connections that you need. This is where VTP really helps as you only need to create the VLAN once, then log into the switches where you're connecting the equipment to assign the access port. The path itself is taken care of automagically.