Chapter 11 Configuring Vtp; Understanding Vtp - Cisco Catalyst 3750 Software Configuration Manual

Metro switch

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Configuring VTP

This chapter describes how to use the VLAN Trunking Protocol (VTP) and the VLAN database for

managing VLANs with the Catalyst 3750 Metro switch.

For complete syntax and usage information for the commands used in this chapter, refer to the command

reference for this release.

The chapter includes these sections:

VTP is a Layer 2 messaging protocol that maintains VLAN configuration consistency by managing the

addition, deletion, and renaming of VLANs on a network-wide basis. VTP minimizes misconfigurations

and configuration inconsistencies that can cause several problems, such as duplicate VLAN names,

incorrect VLAN-type specifications, and security violations.

Before you create VLANs, you must decide whether to use VTP in your network. Using VTP, you can

make configuration changes centrally on one or more switches and have those changes automatically

communicated to all the other switches in the network. Without VTP, you cannot send information about

VLANs to other switches.

VTP is designed to work in an environment where updates are made on a single switch and are sent

through VTP to other switches in the domain. It does not work well in a situation where multiple updates

to the VLAN database occur simultaneously on switches in the same domain, which would result in an

inconsistency in the VLAN database.

The switch supports 1005 VLANs, but the number of routed ports, SVIs, and other 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.

VTP only learns about normal-range VLANs (VLAN IDs 1 to 1005). Extended-range VLANs (VLAN

IDs greater than 1005) are not supported by VTP or stored in the VTP VLAN database.

Understanding VTP, page 11-1

Configuring VTP, page 11-6

Monitoring VTP, page 11-16

C H A P T E R

Catalyst 3750 Metro Switch Software Configuration Guide

Troubleshooting