User's Guide

EMG1302-R10A User’s Guide 103
CHAPTER 11
Quality of Service (QoS)
11.1 Overview
Use the QoS screen to set up your EMG1302-R10A 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 EMG1302-R10A 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 EMG1302-R10A 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.
In the following figure, your Internet connection has an upstream transmission speed of 50 Mbps.
You configure a classifier to assign the highest priority queue (6) to VoIP traffic from the LAN
interface, so that voice traffic would not get delayed when there is network congestion. Traffic from
the boss’s IP address (192.168.1.23 for example) is mapped to queue 5. Traffic that does not
match these two classes are assigned priority queue based on the internal QoS mapping table on
the EMG1302-R10A.
Figure 54 QoS Example
50 Mbps
DSL
VoIP: Queue 6
Boss: Queue 5
IP=192.168.1.23