90 CHAPTER 5: C ONFIGURING AND M ANAGING P ORTS AND VLANSBecause the default VLAN (VLAN 1) might not be in the same subnet oneach switch, 3Com recommends that you do not rename the defaultVLAN or use it for user traffic. Instead, configure other VLANs for usertraffic.Traffic ForwardingA WX switch switches traffic at Layer 2 among ports in the same VLAN.For example, suppose you configure ports 4 and 5 to belong to VLAN 2and ports 6 and 7 to belong to VLAN 3. As a result, traffic between port 4and port 5 is switched, but traffic between port 4 and port 6 is notswitched and needs to be routed by an external router.802.1Q TaggingThe tagging capabilities of the WX switch are very flexible. You can assign802.1Q tag values on a per-VLAN, per-port basis. The same VLAN canhave different tag values on different ports. In addition, the same tagvalue can be 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. MSS does not require the VLAN number and tag valueto be the same, but some other 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.MSS automatically assigns tag values to Distributed MAPs. Each of thesetag values represents a unique combination of radio, encryption type, andVLAN. These tag values do not necessarily correspond to tag values youconfigure on the VLAN ports through which the Distributed MAP isconnected to the WX.Tunnel AffinityWX switches configured as a Mobility Domain allow users to roamseamlessly across MAPs and even across WX switches. Although a switchthat is not a member of a user’s VLAN cannot directly forward traffic forthe user, the switch can tunnel the traffic to another WX switch that is amember of the user’s VLAN.
