ZyXEL Communications VSG1435-B101 - V1.10, Manual

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VSG1435-B101 Series User’s Guide
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Quality of Service (QoS)
10.1 Overview
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.
Configure QoS on the ZyXEL Device to group and prioritize application traffic and
fine-tune network performance. Setting up QoS involves these steps:
1
Configure classifiers to sort traffic into different flows.
2
Assign priority and define actions to be performed for a classified traffic flow.
The ZyXEL Device assigns each packet a priority and then queues the packet
accordingly. Packets assigned a high priority are processed more quickly than
those with low priority if there is congestion, allowing time-sensitive applications
to flow more smoothly. Time-sensitive applications include both those that require
a low level of latency (delay) and a low level of jitter (variations in delay) such as
Voice over IP (VoIP) or Internet gaming, and those for which jitter alone is a
problem such as Internet radio or streaming video.
This chapter contains information about configuring QoS and editing classifiers.
10.1.1 What You Can Do in this Chapter
• The General screen lets you enable or disable QoS and set the
upstream
bandwidth
( Section 10.3 on page 157 ).
• The Queue Setup screen lets you configure QoS queue assignment ( Section
10.4 on page 158 ).
• The Class Setup screen lets you add, edit or delete QoS classifiers ( Section
10.5 on page 161 ).
• The Policer Setup screen lets you add, edit or delete QoS policers ( Section
10.5 on page 161 ).