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C H A P T E R
12-1
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
12
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 your Catalyst 3550 switch. It includes information
about VLAN modes and the VLAN Membership Policy Server (VMPS).
Note
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:
•
Understanding VLANs, page 12-1
•
Configuring Normal-Range VLANs, page 12-4
•
Configuring Extended-Range VLANs, page 12-12
•
•
Configuring VLAN Trunks, page 12-16
•
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 bridge as
shown in
. 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
and
Chapter 17, “Configuring MSTP.”
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