ZyXEL Communications P-661H-61, Manual, Page: 177 / 404

P-661HNU-Fx User’s Guide
177
C
H A P T E R
1 0
Quality of Service (QoS)
10.1 Overview
This chapter discusses the ZyXEL Device’s QoS screens. Use these screens to set
up your ZyXEL Device to use QoS for traffic management.
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. QoS allows the ZyXEL Device to group and prioritize application traffic
and fine-tune network performance.
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.
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
Internet gaming, and those for which jitter alone is a problem such as Internet
radio or streaming video.
10.1.1 What You Can Do in this Chapter
• Use the General screen to enable QoS, set the bandwidth, and allow the ZyXEL
Device to automatically assign priority to upstream traffic according to the IEEE
802.1p priority level, IP precedence or packet length ( Section 10.2 on page
178 ).
• Use the Queue Setup screen to configure QoS queue assignment ( Section 10.3
on page 180 ).
• Use the Class Setup screen to set up classifiers to sort traffic into different
flows and assign priority and define actions to be performed for a classified
traffic flow ( Section 10.4 on page 181 ).
• Use the Monitor screen to view the ZyXEL Device’s QoS-related packet
statistics ( Section 10.5 on page 186 ).