Nortel Networks NN43001-563 - Manual (Page 95)

IP Trunk 3.01 (and later) traffic engineering 95
2. Assess WAN link resources. If resources in the corporate intranet are
not sufficient to adequately support voice services, the cause is usually
insufficient WAN resources.
"Assess WAN link resources" (page 122)
outlines how this assessment can be made.
3. Measure the existing intranet’s Quality of Service (QoS). Estimate the
quality of voice service the corporate intranet can deliver. "Measure
intranet QoS" (page 140) describes how to measure prevailing delay
and error characteristics of an intranet.
After the assessment phase, the IP Trunk 3.01 (and later) network can be
designed and implemented. This design not only involves the IP Trunk
3.01 (and later) elements, but can also require making design changes to
the existing customer intranet.
"Fine-tune network QoS" (page 133) and
"Implement QoS in IP networks" (page 127) provide guidelines for making
modifications to the intranet.
IP Trunk 3.01 (and later) traffic engineering
To design a network is to size the network so that it can accept a calculated
amount of traffic. The purpose of the IP Trunk 3.01 (and later) network is
to deliver voice traffic that meets QoS objectives. Since traffic determines
network design, the design process must start with obtaining an offered IP
Trunk 3.01 (and later) traffic forecast. The traffic forecast drives drive the
following:
• IP Trunk 3.01 (and later) hardware requirements
• WAN requirements
• TLAN subnet requirements
Traffic forecasting is a process that often requires several tries to achieve
satisfactory results. For example, a WAN might not have enough bandwidth
to support all the IP trunks required; therefore the codec choice or the
number of trunks provisioned must be adjusted.
Estimate voice traffic calculations
Follow the steps in Procedure 4 "Estimating voice traffic" (page 95) to
calculate an estimate of voice traffic.
Procedure 4
Estimating voice traffic
Step Action
1 Calculate Voice on IP traffic.
CCS/user=# of calls/ * Average Holding Time (in seconds)/100
Total voice CCS (Tv) = CCS/user x No. of VoIP users
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
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