CLI Reference Guide

Configuring VLANs 191
VLAN Names
To create a VLAN, you must assign a name to it. VLAN names must be
globally unique across a Mobility Domain to ensure the intended user
connectivity as determined through authentication and authorization.
Every VLAN on a WX has a VLAN name, used for authorization purposes,
and a VLAN number. VLAN numbers can vary uniquely for each WX and
are not related to 802.1Q tag values even when used.
You cannot use a number as the first character in a VLAN name.
Roaming and VLANs
WX switches in a Mobility Domain contain a user’s traffic within the
VLAN the user is assigned to. For example, if you assign a user to VLAN
red, the WX switches in the Mobility Domain contain the user’s traffic
within VLAN red configured on the WX switches.
The WX switch through which a user is authenticated must be a member
of the Mobility Domain the user is assigned to. However, you are not
required to configure the VLAN on all WX switches in the Mobility
Domain. When a user roams to a WX switch that is not a member of the
VLAN the user is assigned to, the WX switch can tunnel traffic for the
user through another WX switch that is a member of the VLAN. (For
more information about Mobility Domains, see “Defining a Mobility
Domain” on page 90.)
Because the default VLAN might not be in the same subnet on each WX
switch, 3Com recommends that you do not rename the default VLAN or
use 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. For
example, suppose you configure ports 4 and 5 to belong to VLAN 2 and
ports 6 and 7 to belong to VLAN 3. As a result, traffic between port 4 and
port 5 is switched, but traffic between port 4 and 6 needs to be routed by
an external router.
802.1Q Tagging The tagging capabilities of the WX are flexible. You can assign 802.1Q
tag values on a per-VLAN, per-port basis. The same VLAN can have
different tag values on different ports. In addition, the same tag value can
be used by different VLANs but on different network ports.