Nortel Networks NN43001-563 - Manual (Page 129)

Implement QoS in IP networks 129
and ebb in traffic flows. WAN links appear to be congested at one period
of time time and then are followed by a period of under-utilization. There
are two consequences, as follows:
• WAN link inefficiency
• IP Trunk 3.01 (and later) traffic streams are unfairly affected
IP Trunk 3.01 (and later) DiffServ support for IP QoS
If the intranet provides differentiated services based on the DiffServ/TOS
field, then the IP Trunk 3.01 (and later) traffic and other traffic marked with
this DiffServ/TOS value can be delivered with the goal of meeting this class
of traffic’s QoS objectives.
Configure the DiffServ/TOS value for signaling and voice packets to obtain
better QoS over the IP data network (LAN/WAN).
The Differentiated Service (DiffServ) Code Point (DSCP) determines the
priority of the control and voice packets in the network router queues.
ATTENTION
The values entered in these two fields must be coordinated across the entire IP
data network. Do not change them arbitrarily.
DiffServ values must first be converted to a decimal value of the DiffServ
byte in the IP packet header.
Table 24 "Recommended DiffServ classes"
(page 129) shows the recommended DiffServ traffic classes for various
applications.
Table 24
Recommended DiffServ classes
Traffic type DiffServ class
DSCP
(binary)
DSCP
(decimal)
Voice media Expedited
Forwarding
101110 46
Voice signaling Class Selector 5 101000 40
Data traffic default 000000 0
The DSCP comprises 6 bits within the 8-bit TOS field.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.