122 Configuring and managing ports and VLANs

NN47250-500 (Version 03.01)

802.1Q tagging

The tagging capabilities of the WSS 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, Nortel recommends that you use the same value as the VLAN number. WSS Software
does not require the VLAN number and tag value to be the same, but some other vendors’ devices do.
WSS Software automatically assigns tag values to Distributed APs. 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 AP is connected to the WSS.

Tunnel affinity

WSSs configured as a Mobility Domain allow users to roam seamlessly across APs and even across WSSs.
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 WSS that is a member of the user’s VLAN.
If the WSS that is not in the user’s VLAN has a choice of more than one other WSS through which to tunnel
the user’s traffic, the switch selects the other switch based on an affinity value. This is a numeric value that
each WSS within a Mobility Domain advertises, for each of its VLANs, to all other switches in the Mobility
Domain. A switch outside the user’s VLAN selects the other operational switch that has the highest affinity
value for the user’s VLAN to forward traffic for the user.
If more than one WSS has the highest affinity value, WSS Software randomly selects one of the switches for
the tunnel.
Note. Do not assign the same VLAN multiple times using different tag values to the
same network port. Although WSS Software does not prohibit you from doing so, the
configuration is not supported.