Allied Telesis AT-S63 - Manual (Page 250)

Chapter 18: Quality of Service (QoS) Commands
250 Section I: Basic Features
ˆ Classifiers - Define the traffic flow by specifying the IP address of the
node with the voice application. The classifier for Policy 6 specifies the
address as a source address since this classifier is part of a policy
concerning packets coming from the application. The classifier for
Policy 11 specifies the address as a destination address since this
classifier is part of a policy concerning packets going to the application.
ˆ Flow Groups - Specify the new priority level of 7 for the packets. It
should be noted that in this example the packets leave the switch with
the same priority level they had when they entered. The new priority
level is relevant only as the packets traverse the switch. To alter the
packets so that they leave containing the new level, you would use the
REMARKPRIORITY option in the CREATE QOS FLOWGROUP
command.
ˆ Traffic Classes - No action is taken by the traffic classes, other than to
specify the flow groups. Traffic class has a priority setting that can be
used to override the priority level of packets, just as in a flow group. If
you enter a priority value both in the flow group and the traffic class,
the value in the flow group overrides the value in the traffic class.
ˆ Policies - Specify the traffic class and the port to which the policy is to
be assigned. Policy 6 is applied to port 1 since this is where the
application is located. Policy 11 is applied to port 8 since this is where
traffic going to the application will be received on the switch.
Example 2: Video Application
Video applications typically require a larger bandwidth than voice
applications. Video applications can be set up to have a high priority and
buffering, depending on the application.
This example creates policies with low latency and jitter for video streams
(for example, net conference calls). The policies assign the packets a
priority level of 4 and limit the bandwidth to 5 Mbps. The node containing
the application has the IP address 149.44.44.44. Policy 17 is assigned to
port 1, where the application is located, and Policy 32 is assigned to port 8
where packets destined to the application enter the switch.
Policy 17 Commands:
create classifier=16 description=”video flow”
ipsadddr=149.44.44.44
create qos flowgroup=41 description=”video flow”
priority=4 classifierlist=16
create qos trafficclass=19 description=”video flow”
maxbandwidth=5 flowgrouplist=41
create qos policy=17 description=”video flow”
trafficclasslist=19 ingressport=1