Cisco BR1400 Deployment Manual page 15

4) Add the VLANs: Add the VLANs defined on the switches to the Root and Non Root Bridges.
Like for the above figure, VLANs 11, 12 and 14 have to be added on the Bridges as well, so that
these VLANs can be trunked through the wireless link.
QoS
3.2
Implementing QoS in your wireless link makes network performance more predictable and
bandwidth utilization more effective. By using QoS feature you can prioritize a specific type of
traffic instead of making it a purely FIFO (first in, first out). This is due to the fact that voice/video
traffic when subject to delays causes very unfavorable behavior in phone conversations (major lags
or even dropped phone calls). This is also true with other types of traffic such as video traffic
(which is what we will be testing here in this situation).
The following are the objectives of the QoS feature supported in 1400 bridge:
• Provide 802.1p priority bits and 802.1q VLAN tag based QoS
• Provide priority services for VOIP traffic, based upon IP TOS/DSCP
The bridge can only classify traffic based on IP TOS (Type of service bits in IP protocol header)
Precedence and DSCP (differentiated services code point) values and put it into the correct priority
queues. It has 8 priority queues corresponding to eight 802.11E priority values. The CoS values
associated with the eight priority queues are the same as the 802.1d
User priority values that are carried in an Ethernet frame, an 802.1q priority tag or an 802.1q
VLAN tag. The CoS value is used to select the appropriate 802.11 transmit queue.
The bridge uses the radio traffic class definitions to calculate back off times for each packet. As a
rule, high-priority packets have short back off times. The default values in the Min and Max
Contention Window fields and in the Slot Time fields are based on settings recommended in IEEE
Draft Standard 802.11e.
We can modify the CwMin and CwMax values depending upon the type of the network and our
needs.
QoS works even with packet concatenation enabled.
The steps to configure QoS are:
1) First create a QoS policy. Go to services in GUI interface and define a policy.
Copyright © 2004 Cisco Systems, Inc. All rights reserved.
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