Qos; Chapter 9 Qos; Overview; What You Need To Know - ZyXEL Communications GS1200 SERIES User Manual

9.1 Overview

This chapter introduces the configuration and functions of the QoS (Quality of Service) screen.
The QoS (Quality of Service) feature allows you to prioritize the flow of data passing through the
Switch. Occasionally, data might be delayed, depending on the volume of traffic and the capacity of
the equipment. Numeric and text data are usually not affected by delays, because they are
reassembled at the destination. However, when VoIP and streaming videos are reassembled, they
might have some troublesome gaps. 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 applications such as VOD (Video on Demand).
You can enable QoS to have the Switch assign 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.
The QoS feature in the Switch is disabled by default.
Figure 16 QoS Default Screen

9.2 What You Need to Know

The Switch can put packets into the queues according to the port on which the packet is received or
the priority tag in the packet.
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QoS