ZyXEL Communications VMG4325-B10A, User Manual

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VMG4380-B10A / VMG4325-B10A 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 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 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 163 ).
• The Queue Setup screen lets you configure QoS queue assignment ( Section 10.4 on page 164 ).
• The Class Setup screen lets you add, edit or delete QoS classifiers ( Section 10.5 on page 166 ).
• The Policer Setup screen lets you add, edit or delete QoS policers ( Section 10.5 on page 166 ).
• The Monitor screen lets you view the Device's QoS-related packet statistics ( Section 10.7 on
page 173 ).