ZyXEL Communications EMG3425-Q10A, Руководство пользователя

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EMG3425-Q10A User’s Guide
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Bandwidth Management
20.1 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 EMG3425-Q10A 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 EMG3425-Q10A 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.
20.1.1 What You Can Do in this Chapter
• The General screen lets you enable or disable QoS and set the upstream bandwidth ( Section
20.3 on page 135 ).
• The Queue Setup screen lets you configure QoS queue assignment ( Section 20.4 on page 136 ).
• The Class Setup screen lets you add, edit or delete QoS classifiers ( Section 20.5 on page 138 ).
20.2 What You Need to Know
The following terms and concepts may help as you read through this chapter.
QoS versus CoS
QoS is used to prioritize source-to-destination traffic flows. All packets in the same flow are given
the same priority. CoS (class of service) is a way of managing traffic in a network by grouping