Motorola WiNG 4.4 Reference Manual page 30

1 - 14 WiNG 4.4 Switch System Reference Guide
Data QoS
The switch supports the following data QoS techniques:
• Egress Prioritization by WLAN
• Egress Prioritization by ACL
DCSCP to AC Mapping
The switch provides arbitrary mapping between Differentiated Services Code Point (DCSCP) values and WMM Access
Categories. This mapping can be set manually.
1.2.2.14 Wireless Layer 2 Switching
The switch supports the following layer 2 wireless switching techniques:
• WLAN to VLAN
• MU User to VLAN
• WLAN to GRE
1.2.2.15 Automatic Channel Selection
Automatic channel selection works sequentially as follows:
1. When a new AP is adopted, it scans each channel. However, the switch does not forward traffic at this time.
2. The switch then selects the least crowded channel based on the noise and traffic detected on each channel.
3. The algorithm used is a simplified maximum entropy algorithm for each radio, where the signal strength from adjoining
AP's/MU's associated to adjoining AP's is minimized.
4. The algorithm ensures adjoining AP's are as far away from each other as possible (in terms of channel assignment).
NOTE: Individual radios can be configured to perform automatic channel selection.
1.2.2.16 WMM-Unscheduled APSD
This feature is also known as WMM Power Save or WMM-UPSD (Unscheduled Power Save Delivery). WMM-UPSD
defines an unscheduled service period, which are contiguous periods of time during which the switch is expected to be
awake. If the switch establishes a downlink flow and specifies UPSD power management, it requests (and the AP delivers)
buffered frames associated with that flow during an unscheduled service period. The switch initiates an unscheduled
service period by transmitting a trigger frame. A trigger frame is defined as a data frame (e.g. an uplink voice frame)
associated with an uplink flow with UPSD enabled. After the AP acknowledges the trigger frame, it transmits the frames
in its UPSD power save buffer addressed to the triggering switch.
UPSD is well suited to support bi-directional frame exchanges between a voice STA and its AP.
1.2.2.17 Multiple VLANs per WLAN
The switch permits the mapping of a WLAN to more than one VLAN. When a MU associates with a WLAN, the MU is
assigned a VLAN by means of load balance distribution. The VLAN is picked from a pool assigned to the WLAN. The switch
tracks the number of MUs per VLAN, and assigns the least used/loaded VLAN to the MU. This number is tracked on a per-
WLAN basis.
A broadcast key, unique to the VLAN, encrypts packets coming from the VLAN. If two or more MUs are on two different
VLANs, they both hear the broadcast packet, but only one can decrypt it. The switch provides each MU a unique VLAN
broadcast key as part of the WPA2 handshake or group key update message of a WPA handshake.