Time critical data traffic such as voice and video benefit from Quality of
Service (QoS), which can be configured to give voice and video higher priority.
This allows for smooth voice communication, jitter free video, and reliable
delivery of E-Mail configured with a lower priority
.
Cisco
uses the same Class of Service (CoS) used on Cisco Routers. At this time Cisco
can only support downstream (Access Point to Client) QoS. When 802.11e QoS
becomes ratified, Cisco will also support upstream (Client to Access Point) QoS
as well by simply upgrading the firmware.
Class of Service (CoS) uses
the 802.1P standard to set the priority field to network traffic. There are
eight different types of CoS traffic values that can be assigned different
network traffic
.
802.11e is supplementary to the MAC layer to provide QoS support for LAN
applications. It will apply to 802.11 physical standards a, b, and g. The
purpose is to provide classes of service with managed levels of QoS for data,
voice, and video applications.
802.11e has two components:
- Enhanced Distributed Coordination Function (eDCF) which is responsible for
prioritization.
- Transmission Opportunity (TXOP) which is responsible for transmission
control.