C H A P T E R
12-1
Cisco Catalyst Blade Switch 3120 for HP Software Configuration Guide
OL-12247-01
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 the 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
standalone switch and to a 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 12-1
•
Configuring Normal-Range VLANs, page 12-4
•
Configuring Extended-Range VLANs, page 12-12
•
Displaying VLANs, page 12-16
•
Configuring VLAN Trunks, page 12-16
•
Configuring VMPS, page 12-28
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 12-1
. 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 17, “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 13,
“Configuring VTP.”