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VMG5313-B10A/-B30A Series User’s Guide
163
CHAPTER 10
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 VMG 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 VMG 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 165).
•The Queue Setup screen lets you configure QoS queue assignment (Section 10.4 on page 166).
•The Class Setup screen lets you add, edit or delete QoS classifiers (Section 10.5 on page 168).
•The Policer Setup screen lets you add, edit or delete QoS policers (Section 10.5 on page 168).
10.2 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