190 CHAPTER 5: C ONFIGURING WX S YSTEM AND ADMINISTRATIVE P ARAMETERSThe WX switch through which a user is authenticated must be a memberof the Mobility Domain the user is assigned to. However, you are notrequired to configure the VLAN on all WX switches in the MobilityDomain. When a user roams to a WX switch that is not a member of theVLAN the user is assigned to, the WX switch can tunnel traffic for theuser through another WX switch that is a member of the VLAN. (Formore information about Mobility Domains, see “Defining a MobilityDomain” on page 88.)Because the default VLAN might not be in the same subnet on each WXswitch, 3Com recommends that you do not rename the default VLAN oruse it for user traffic. Instead, configure other VLANs for user traffic.Traffic Forwarding A WX switches traffic at Layer 2 among ports in the same VLAN. Forexample, suppose you configure ports 4 and 5 to belong to VLAN 2 andports 6 and 7 to belong to VLAN 3. As a result, traffic between port 4 andport 5 is switched, but traffic between port 4 and 6 needs to be routed byan external router.802.1Q Tagging The tagging capabilities of the WX are flexible. You can assign 802.1Qtag values on a per-VLAN, per-port basis. The same VLAN can havedifferent tag values on different ports. In addition, the same tag value canbe used by different VLANs but on different network ports.If you use a tag value, 3Com recommends that you use the same value asthe VLAN number. The WX switch does not require the VLAN numberand tag value to be the same, but some other vendors’ devices do.Do not assign the same VLAN multiple times using different tag values tothe same network port. Although MSS does not prohibit you from doingso, the configuration is not supported.Creating a VLAN You create a VLAN by using the Create VLAN wizard, which allows you todo the following: Configure basic VLAN properties.■ Add ports to a VLAN.■ Configure Spanning Tree Protocol (STP).■ Configure STP port information.■ Configure Internet Group Management Protocol (IGMP).■ Configure static multicast port information.
