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Software Configuration Guide—Release 12.2(25)SG
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Chapter10 Understanding and Configuring VLANs, VTP, andVMPS
VLAN Trunking Protocol

Assigning a Layer 2 LAN Interface to a VLAN

A VLAN created in a management domain remains unused until you assign one or more LAN interfaces
to the VLAN.
Note Make sure you assign LAN interfaces to a VLAN of the prop er type. Assign Fast Ethernet, Gigabit
Ethernet, and 10-Gigabit Ethernet interfaces to Ethernet-type VLANs.
To assign one or more LAN interfaces to a VLAN, complete the procedures in the “Configuring Ethernet
Interfaces for Layer 2 Switching” section on page 11-5.
VLAN Trunking Protocol
This section describes the VLAN Trunking Protocol (VTP) on the Cataly st 4500 series switches.
This section includes the following major subsections:
Overview of VTP, page 10-8
VTP Configuration Guidelines and Restrictions, page 10-12
VTP Default Configuration, page 10-12
Configuring VTP, page 10-13

Overview of VTP

VTP is a Layer 2 messaging protocol that maintains VLAN configuration c onsistency by managing the
addition, deletion, and renaming of VLANs within a VTP domain. A VTP domain (also called a VLAN
management domain) is made up of one or more network devices that share the same VTP domain name
and that are interconnected with trunks. VTP minimizes misconfigurations and configuration
inconsistencies that can result in a number of problems, such as duplicate VLAN names, incorrec t
VLAN-type specifications, and security violations.
Before you create VLANs, you must decide whether you want to use VTP in your network. With VTP,
you can make configuration changes centrally on one or more network devices and have those changes
automatically communicated to all the other network devices in the network. For details on configuring
VLANs, see VLANs, page 10-1
These sections describe how VTP works:
Understanding the VTP Domain, page 10-9
Understanding VTP Modes, page 10-9
Understanding VTP Advertisements, page 10-9
Understanding VTP Version 2, page 10-10
Understanding VTP Pruning, page 10-10