CHAPTER
14-1
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
14

Configuring VLANs

This c hapt er d escri b es how to c onfigure norm al -ra nge V LAN s (V L AN IDs 1 to 100 5) and
extended-range VLANs (VLAN IDs 1006 to 4094). It includes information about VLAN modes and the
VLAN Membership Policy Server (VMPS).
Note For comple te syntax and us age inform ation for the co mmands used in this chapter, refer to th e command
refere nce fo r thi s r ele ase.
The ch apt er inc ludes th ese sect ions:
•Understa ndin g VL ANs, pag e 14- 1
•Configuring Normal-Ra nge VLAN s, page 14 -4
•Configuring Ext ende d-R an ge V LAN s, page 14-12
•Displaying VLANs, page 14-14
•Configuring VL AN Trunks, page 14-15
•Configuring V MPS, pa ge 14 -24

Understandin g VLANs

A VLAN is a switched network that is logically segmented by function, project team, or application,
without re gard to the ph ysical locations of th e users. VLANs ha ve the same attrib utes as ph ysical LANs,
but you can gro up en d s tations even if they a re no t phy sica lly loc ated on the same LAN segment . A ny
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 f or stat ion s t hat d o n ot b elon g to the VL AN mu st be f orwar de d thr oug h a rou t er or b ridge as
shown in Figure 14-1. Because a VLAN is considered a separate logical network, it contains its own
bridge Man agem en t I nfo rmat ion Base (M IB ) in for mat ion an d c an s uppo rt i ts own impl eme ntat ion o f
spannin g tr ee . See Cha pter 11, “Configuring STP” and Chapter 12, “Configuring RSTP and MSTP.”
Note Before you create VLANs, you must decide whether to use VLAN T runking Protocol (VTP) to maintain
global VL AN configurat ion for you r network. For more informat ion on VTP, see Chapte r 15,
“Configuring V TP.”