Nortel Networks NN43001-563 - Manual (Page 152)

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
.