CHAPT ER
15-1
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
15
Configuring VLANs
This chapter describes how to configure normal-range VLANs (VLAN IDs 1 to 1005) and
extended-range VLANs (VLAN IDs 1006 to 4094) on the Catalyst 3750-X or 3560-X switch. It includes
information about VLAN membership modes, VLAN configuration modes, VLAN trunks, and dynamic
VLAN assignment from a VLAN Membership Policy Server (VMPS). Unless otherwise noted, the term
switch refers to a Catalyst 3750-X or 3560-X standalone switch and to a Catalyst 3750-X switch stack.
Note 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:
Understanding VLANs, page 15-1
Configuring Normal-Range VLANs, page 15-4
Configuring Extended-Range VLANs, page 15-10
Displaying VLANs, page 15-14
Configuring VLAN Trunks, page 15-14
Configuring VMPS, page 15-25

Understanding VLANs

A VLAN is a switched network that is logically segmented by function, project team, or application,
without regard to the physical locations of the users. VLANs have the same attributes as physical LANs,
but you can group end stations even if they are not physically located on the same LAN segment. Any
switch port can belong to a VLAN, and unicast, broadcast, and multicast packets are forwarded and
flooded only to end stations in the VLAN. Each VLAN is considered a logical network, and packets
destined for stations that do not belong to the VLAN must be forwarded through a router or a switch
supporting fallback bridging, as shown in Figure 15-1. In a switch stack, VLANs can be formed with
ports across the stack. Because a VLAN is considered a separate logical network, it contains its own
bridge Management Information Base (MIB) information and can support its own implementation of
spanning tree. See Chapter 20, “Configuring STP.”
Note Before you create VLANs, you must decide whether to use VLAN Trunking Protocol (VTP) to maintain
global VLAN configuration for your network. For more information on VTP, see Chapter 16,
“Configuring VTP.”