ZyXEL Communications X2002, User Manual

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Chapter 8 QoS
X2002 User’s Guide
169
Expedited Forwarding (EF) - The EF PHB defines a single DSCP designed for
simulating a private end-to-end pipeline across a DiffServ network. IP packets are
marked for high priority low-loss, low-latency, low-jitter, assured-bandwidth end
to end service through DS domains. This is recommended for use with VoIP traffic
as it addresses the factors that cause degradation in sound quality.
Class Selector (CS) - IP packets are marked with values partially backwards-
compatible with known current uses of IP precedence field. The packets marked
with higher values are given higher priority than those with lower values.
8.1.3 Before You Begin
Before you start configuring QoS on your X2002, you should know the type of QoS
your network uses, and the relevant setting that you want to assign to the
X2002’s traffic.
8.2 The QoS Screen
Use this screen to set up the QoS settings on the X2002. To access this screen,
click
Configuration > PBX > Server Configuration > QoS .
Figure 76 Server Configuration > QoS
Each field is described in the following table.
Table 41 Server Configuration > QoS
LABEL DESCRIPTION
QoS Select the QoS method you want to use to mark outgoing frames on the
X2002.
You can choose:
• TOS and then select one of the four classes of service supported on
the X2002: minimize delay , maximize throughput , maximize
reliability or minimize cost .
• DS (DiffServ) and then select the DSCP value to mark the outgoing
packets. You can choose: one of the AF (Assured Forwarding), EF
(Expedited Forwarding) or one of the CS (Class Selector) values.
• User Define and then enter a value to assign to the ToS field in
decimal notation. You can set the value to a value from 0 to 255. The
X2002 displays the value you enter in hexadecimal notation.
• None , if you do not want to mark the ToS field of the outgoing VoIP
packets.
Apply Click this to save your changes.
Reset Click this to set every field in this screen to its last-saved value.