ZyXEL Communications P-660HN-F1 User Manual
P-660HN-F1 User’s Guide
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Quality of Service (QoS)
15.1 Overview
Use the QoS 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 bandwidth. QoS allows the ZyXEL Device to
group and prioritize application traffic and fine-tune network performance.
and the networking methods used to control bandwidth. QoS allows the ZyXEL Device to
group and prioritize application traffic and fine-tune network performance.
Without QoS, all traffic data are 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 video-on-demand.
This can cause a reduction in network performance and make the network inadequate for time-
critical applications such as video-on-demand.
The ZyXEL Device assigns each packet a priority and then queues the packet accordingly.
Packets assigned with a high priority are processed more quickly than those with low priorities
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.
Packets assigned with a high priority are processed more quickly than those with low priorities
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.
15.1.1 What You Can Do in the QoS Screens
• Use the General screen (
) to enable QoS on the ZyXEL Device,
decide allowable bandwidth using QoS and configure priority mapping settings for traffic
that does not match a custom class.
that does not match a custom class.
• 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.
traffic flow.
• Use the Monitor screen (
) to view the ZyXEL Device’s QoS-
related packet statistics.
15.1.2 What You Need to Know About QoS
QoS versus Cos
QoS is used to prioritize source-to-destination traffic flows. All packets in the same flow are
given the same priority. Class of Service (CoS) is a way of managing traffic in a network by
grouping similar types of traffic together and treating each type as a class. You can use CoS to
give different priorities to different packet types.
given the same priority. Class of Service (CoS) is a way of managing traffic in a network by
grouping similar types of traffic together and treating each type as a class. You can use CoS to
give different priorities to different packet types.