SMC Networks WBR14S-N3 - annexe 1 Manual page 60

5
System Configuration
• APSD Capable – Auto Power Save Delivery is used for saving power
consumption. APSD allows a longer beacon interval until the traffic arrives.
(Default: Disable.
• DLS Capable – The Direct Link Setup (DLS) allows all clients transfer data more
effectively. When enables DLS, the wireless AP/Router will all clients on this unit to
establish directly connection and speed up the data transmission, especially for
multimedia data files. (Default: Disable)
• WMM Parameters – Display the WMM Parameters.
Access Categories – WMM defines four access categories (ACs): voice, video,
best effort, and background. These categories correspond to traffic priority levels
and are mapped to IEEE 802.1D priority tags (see Table 5-1). The direct mapping of
the four ACs to 802.1D priorities is specifically intended to facilitate inter operability
with other wired network QoS policies. While the four ACs are specified for specific
types of traffic, WMM allows the priority levels to be configured to match any
network-wide QoS policy. WMM also specifies a protocol that access points can use
to communicate the configured traffic priority levels to QoS-enabled wireless clients.
Access Category WMM Designation Description
AC_VO (AC3)
AC_VI (AC2)
AC_BE (AC0)
AC_BK (AC1)
WMM Operation — WMM uses traffic priority based on the four ACs; Voice, Video,
Best Effort, and Background. The higher the AC priority, the higher the probability
that data is transmitted. When the access point forwards traffic, WMM adds data
packets to four independent transmit queues, one for each AC, depending on the
802.1D priority tag of the packet. Data packets without a priority tag are always
added to the Best Effort AC queue. From the four queues, an internal "virtual"
collision resolution mechanism first selects data with the highest priority to be
granted a transmit opportunity. Then the same collision resolution mechanism is
used externally to determine which device has access to the wireless medium.
5-26
, See "Beacon Interval" on page 5-24
Table 5-2. WMM Access Categories
Voice Highest priority, minimum delay. Time-sensitive
data such as VoIP (Voice over IP) calls.
Video High priority, minimum delay. Time-sensitive data
such as streaming video.
Best Effort Normal priority, medium delay and throughput.
Data only affected by long delays. Data from
applications or devices that lack QoS capabilities.
Background Lowest priority. Data with no delay or throughput
requirements, such as bulk data transfers.
)
802.1D Tags
7, 6
5, 4
0, 3
2, 1