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Catalyst 2960 and 2960-S Switch Software Configuration Guide
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Chapter 14 Configuring VTP
Understanding VTP
The switch supports 255 VLANs, but the number of configured features affects the usage of the switch
hardware. If the switch is notified by VTP of a new VLAN and the switch is already using the maximum
available hardware resources, it sends a message that there are not enough hardware resources available
and shuts down the VLAN. The output of the show vlan user EXEC command shows the VLAN in a
suspended state.
Note The switch supports up to 64 VLANs when it is running the LAN Lite image.
VTP version 1 and version 2 support only normal-range VLANs (VLAN IDs 1 to 1005). Cisco IOS
Release 12.2(52)SE and later support VTP version 3. VTP version 3 suppo rts the entire VLAN range
(VLANs 1 to 4094). Extended range VLANs (VLANs 1006 to 4094) are supported only in VTP
version 3. You cannot convert from VTP version 3 to VTP version 2 if extended VLANs are configured
in the domain.
Note The switch must be running the LAN base image to support VTP version 3.
These sections contain this conceptual information:
• The VTP Domain, page 14-2
• VTP Modes, page 14-3
• VTP Advertisements, page 14-4
• VTP Version 2, page 14-5
• VTP Version 3, page 14-5
• VTP Pruning, page 14-6
The VTP Domain
A VTP domain (also called a VLAN management domain) consis ts of one switch or several
interconnected switches or switch stacks under the same administrative responsibility sharing the same
VTP domain name. A switch can be in only one VTP domain. You make global VLAN configuration
changes for the domain.
By default, the switch is in the VTP no-management-domain state until it receives an advertisement for
a domain over a trunk link (a link that carries the traffic of multiple VLANs) or until you configure a
domain name. Until the management domain name is specified or learned, you cannot create or modify
VLANs on a VTP server, and VLAN information is not propagated over the network.
If the switch receives a VTP advertisement over a trunk link, it inherits the management domain name
and the VTP configuration revision number. The switch then ignores advertisements with a different
domain name or an earlier configuration revision number.
Caution Before adding a VTP client switch to a VTP domain, always verify that its VTP configuration revision
number is lower than the configuration revision number of the other switches in the VTP domain.
Switches in a VTP domain always use the VLAN configuration of the swit ch with the highest VTP
configuration revision number. If you add a switch that has a revision number hig her than the revision
number in the VTP domain, it can erase all VLAN information from the VTP server and VTP domain.
See the “Adding a VTP Client Switch to a VTP Domain” section on page 14-17 for the procedure for
verifying and resetting the VTP configuration revision number.