Qos For Wireless Lans Versus Qos On Wired Lans; Impact Of Qos On A Wireless Lan - Cisco C3201FESMIC-TP= - 3201 Fast EN Switch Mobile Interface Card Expansion Module Software Configuration Manual

Understanding QoS for Wireless LANs

QoS for Wireless LANs Versus QoS on Wired LANs

The QoS implementation for wireless LANs differs from QoS implementations on other Cisco devices.
With QoS enabled, bridges perform the following:
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To contrast the wireless LAN QoS implementation with the QoS implementation on other Cisco network
devices, see the Cisco IOS Quality of Service Solutions Configuration Guide at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqos_c/index.htm

Impact of QoS on a Wireless LAN

Wireless LAN QoS features are a subset of the proposed 802.11e draft. QoS on wireless LANs provides
prioritization of traffic from the WMIC over the WLAN based on traffic classification.
Just as in other media, you might not notice the effects of QoS on a lightly loaded wireless LAN. The
benefits of QoS become more obvious as the load on the wireless LAN increases, keeping the latency,
jitter, and loss for selected traffic types within an acceptable range.
QoS on the wireless LAN focuses on downstream prioritization from the WMIC. These are the effects
of QoS on network traffic:
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Cisco 3200 Series Wireless MIC Software Configuration Guide
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B e t a D r a f t f o r R e v i e w - C i s c o C o n f i d e n t i a l
They do not classify packets; they prioritize packets based on DSCP value, client type (such as a
wireless phone), or the priority value in the 802.1q or 802.1p tag.
They do not match packets using ACL; they use only modular quality of service (MQC) class-map
for matching clauses.
They do not construct internal DSCP values; they only support mapping by assigning IP
Differentiated Services Code Point (DSCP), Precedence, or Protocol values to Layer 2 COS values.
They carry out Enhanced Distributed Coordination Function (EDCF)-like queuing on the radio
egress port only.
They do only FIFO queuing on the Ethernet egress port.
They support only 802.1Q/P tagged packets. Bridges do not support InterSwitch Link Protocol
(ISL).
They support only MQC policy-map set cos action.
The radio downstream flow is traffic transmitted out the WMIC radio to another bridge. This traffic
is the main focus for QoS on a wireless LAN.
The radio upstream flow is traffic received on the WMIC radio from another bridge. QoS for
wireless LAN does not affect this traffic.
The Ethernet downstream flow is traffic sent from a switch or a router to the Ethernet port on the
WMIC. If QoS is enabled on the switch or router, the switch or router might prioritize and rate-limit
traffic to the WMIC.
The Ethernet upstream flow is traffic sent from the WMIC Ethernet port to a switch or router on the
wired LAN. The WMIC does not prioritize traffic that it sends to the wired LAN based on traffic
classification.
QoS in a Wireless Environment