ZyXEL Communications XGS4700 Series, Manual

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XGS4700-48F User’s Guide
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Classifier
This chapter introduces and shows you how to configure the packet classifier on
the Switch.
20.1 About the Classifier and QoS
Quality of Service (QoS) refers to both a network's ability to deliver data with
minimum delay, and the networking methods used to control the use of
bandwidth. Without QoS, all traffic data is equally likely to be dropped when the
network is congested. This can cause a reduction in network performance and
make the network inadequate for time-critical application such as video-on-
demand.
A classifier groups traffic into data flows according to specific criteria such as the
source address, destination address, source port number, destination port number
or incoming port number. For example, you can configure a classifier to select
traffic from the same protocol port (such as Telnet) to form a flow.
Configure QoS on the Switch to group and prioritize application traffic and fine-
tune network performance. Setting up QoS involves two separate steps:
1
Configure classifiers to sort traffic into different flows.
2
Configure policy rules to define actions to be performed for a classified traffic flow
(refer to
Chapter 21 on page 209 to configure policy rules).
You can also configure policy routing to forward a classified traffic flow to a
different gateway for cost savings and load sharing. See
Chapter 35 on page 303
for how to configure policy routing.