ZyXEL Communications eircom D1000, User Manual

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113
eircom D1000 m
odem User’s Guide
8
Quality of Service (QoS)
8.1 Overview
Use the QoS screen to set up your 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 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.
The 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.
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 Device.
Figure 78
QoS Example
VoIP: Queue 6
DSL
50 Mbps
Boss: Queue 5
IP=192.168.1.23
8.1.1 What You Can Do in the QoS Screens
• Use the General screen ( Section 8.2 on page 114 ) to enable QoS on the Device, and specify the
type of scheduling.