Chapter 14 Configuring VTP

Understanding VTP

For domain name and password configuration guidelines, see the “VTP Configuration Guidelines” section on page 14-8.

VTP Modes

 

You can configure a supported switch or switch stack to be in one of the VTP modes listed in Table 14-1.

Table 14-1

VTP Modes

 

 

VTP Mode

Description

 

 

VTP server

In VTP server mode, you can create, modify, and delete VLANs, and specify other configuration

 

parameters (such as the VTP version) for the entire VTP domain. VTP servers advertise their VLAN

 

configurations to other switches in the same VTP domain and synchronize their VLAN configurations with

 

other switches based on advertisements received over trunk links.

 

In VTP server mode, VLAN configurations are saved in NVRAM. VTP server is the default mode.

 

 

VTP client

A VTP client behaves like a VTP server and transmits and receives VTP updates on its trunks, but you

 

cannot create, change, or delete VLANs on a VTP client. VLANs are configured on another switch in the

 

domain that is in server mode.

 

In VTP client mode, VLAN configurations are not saved in NVRAM.

VTP transparent VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on received advertisements. However, in VTP Version 2, transparent switches do forward VTP advertisements that they receive from other switches through their trunk interfaces. You can create, modify, and delete VLANs on a switch in VTP transparent mode.

The switch must be in VTP transparent mode when you create extended-range VLANs. See the “Configuring Extended-Range VLANs” section on page 13-12.

The switch must be in VTP transparent mode when you create private VLANs. See Chapter 16, “Configuring Private VLANs.” When private VLANs are configured, do not change the VTP mode from transparent to client or server mode.

When the switch is in VTP transparent mode, the VTP and VLAN configurations are saved in NVRAM, but they are not advertised to other switches. In this mode, VTP mode and domain name are saved in the switch running configuration, and you can save this information in the switch startup configuration file by using the copy running-configstartup-configprivileged EXEC command. On Catalyst 3750-E switches, the running configuration and the saved configuration are the same for all switches in a stack.

VTP Advertisements

Each switch in the VTP domain sends periodic global configuration advertisements from each trunk port to a reserved multicast address. Neighboring switches receive these advertisements and update their VTP and VLAN configurations as necessary.

Note Because trunk ports send and receive VTP advertisements, you must ensure that at least one trunk port is configured on the switch or switch stack and that this trunk port is connected to the trunk port of another switch. Otherwise, the switch cannot receive any VTP advertisements. For more information on trunk ports, see the “Configuring VLAN Trunks” section on page 13-16.

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

 

OL-9775-02

14-3

 

 

 

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Cisco Systems 3750E manual VTP Modes, VTP Advertisements, VTP Mode Description, 14-3