ZyXEL P-794H User Guide - Page 163

Quality of Service (QoS), 14.1 Overview, 14.1.1 What You Need to Know

Page 163 highlights

CHAPTER 14 Quality of Service (QoS) 14.1 Overview Use the QoS screens to set up your P-794H 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 P-794H 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. The P-794H 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. 14.1.1 What You Need to Know DSCP DiffServ Code Point (DSCP) is a field used for packet classification on DiffServ networks. The higher the value, the higher the priority. Lower-priority packets may be dropped if the total traffic exceeds the capacity of the network. Tagging and Marking In a QoS class, you can configure whether to add or change the DiffServ Code Point (DSCP) value, IEEE 802.1p priority level and VLAN ID number in a matched packet. When the packet passes through a compatible network, the networking device, such as a backbone switch, can provide specific treatment or service based on the tag or marker. P-794H User's Guide 163

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P-794H User’s Guide
163
C
HAPTER
14
Quality of Service (QoS)
14.1
Overview
Use the
QoS
screens to set up your P-794H 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 P-794H 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.
The P-794H 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.
14.1.1
What You Need to Know
DSCP
DiffServ Code Point (DSCP) is a field used for packet classification on DiffServ
networks. The higher the value, the higher the priority. Lower-priority packets
may be dropped if the total traffic exceeds the capacity of the network.
Tagging and Marking
In a QoS class, you can configure whether to add or change the DiffServ Code
Point (DSCP) value, IEEE 802.1p priority level and VLAN ID number in a matched
packet. When the packet passes through a compatible network, the networking
device, such as a backbone switch, can provide specific treatment or service
based on the tag or marker.