Cisco Systems 3560 사용자 설명서

This chapter describes how to use the VLAN Trunking Protocol (VTP) and the VLAN database for 
managing VLANs with the Catalyst 3560 switch. 

For complete syntax and usage information for the commands used in this chapter, see the command 
reference for this release.

The chapter consists of 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.