3Com WX1200 3CRWX120695A, WXR100 3CRWXR10095A Traffic Forwarding, 802.1Q Tagging, Tunnel Affinity

90CHAPTER 5: CONFIGURING AND MANAGING PORTS AND VLANS

Because the default VLAN (VLAN 1) might not be in the same subnet on each 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 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 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 port 6 is not switched and needs to be routed by an external router.

802.1Q Tagging

The tagging capabilities of the WX switch are very 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.

If you use a tag value, 3Com recommends that you use the same value as the VLAN number. MSS does not require the VLAN number and tag value to be the same, but some other devices do.

Do not assign the same VLAN multiple times using different tag values to the same network port. Although MSS does not prohibit you from doing so, the configuration is not supported.

MSS automatically assigns tag values to Distributed MAPs. Each of these tag values represents a unique combination of radio, encryption type, and VLAN. These tag values do not necessarily correspond to tag values you configure on the VLAN ports through which the Distributed MAP is connected to the WX.

Tunnel Affinity

WX switches configured as a Mobility Domain allow users to roam seamlessly across MAPs and even across WX switches. Although a switch that is not a member of a user’s VLAN cannot directly forward traffic for the user, the switch can tunnel the traffic to another WX switch that is a member of the user’s VLAN.