VLAN Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain via trunk links. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst series products.

There are three Versions of VTP.

VTP version 1

• Supports normal VLAN numbers (1-1001)
• Supports pruning of unused VLANs (no longer sends *Broadcasts and unknown unicasts
• Supports cleartext and MD5 digest password

VTP version 2

• Forwards the VTP messages without checking the version number or domain in transparent mode
• Supports Token Ring
• Performs consistency check on the VTP / VLAN parameters (from CLI or SNMP)
• Pass on Unrecognised TLVs

VTP version 3

• Supports extended VLAN numbers (1-4095)
• Transfer information regarding Private VLAN structure
• Support for databases other than VLAN (for example MST)
• Protection from unintended database overrides during insertion of new switches
• Hidden password protection

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