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152 ITG engineering guidelines
To calculate R = 94 - lc - ld - lp, use Table 29 "Impairment factors of codecs"
(page 149), Table 30 "Impairment factors due to network delay" (page 149),
and Table 31 "Impairment factors due to packet loss" (page 149):
•
G.711 codec: lc = 0
•
20 msec network delay: ld = 0
•
0.5% packet loss: lp = 2
Then:
R=94-0-0-2
R=92
Using Table 33 "IP Trunk 3.01 (and later) QoS levels" (page 150), a value of
92 means the users are very satisfied.
Scenario 2 A campus network has the following characteristics:
•
G.711 codec
•
50 msecs delay
•
1.0% packet loss
To calculate R = 94 - lc - ld - lp, use Table 29 "Impairment factors of codecs"
(page 149), Table 30 "Impairment factors due to network delay" (page 149),
and Table 31 "Impairment factors due to packet loss" (page 149):
•
G.711 codec: lc = 0
•
20 msec network delay: ld = 5
•
0.5% packet loss: lp = 4
Then:
R=94-0-5-4
R=85
Using Table 33 "IP Trunk 3.01 (and later) QoS levels" (page 150), a value of
85 means that the users are satisfied.
Scenario 3 A WAN has the following characteristics:
•
G.729 codec
•
30 msec network delay
•
2% packet loss
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.