
Measure intranet QoS 149
This model already takes into account some character istics of the IP Phone,
and therefore the impairment factors are not identical to those shown in
the ITU-T standards.
Refer to Table 32 "R value translation" (page 150) for the translation of R
values into user satisfaction levels.
Table 29
Impairment factors of codecs
Codec
Codec Impairment (lc)
(msec frames)
G.711
0
G.729A/AB
11 - 20 or 30
G.729A/AB
16 - 40 or 50
G.723.1 (5.3 Kbps)
19
G.723.1 (6.3 Kbps)
15
Table 30
Impairment factors due to network delay
Network delay* (msec) Delay Impairment (ld)
0 - 49 0
50 - 99 5
100 -149 10
150 - 199 15
200 - 249 20
250 - 299 25
* Network delay is the average one-way network delay plus packetization and
jitter buffer delay.
Table 31
Impairment factors due to packet loss
Packet loss (%) Packet Lose Impairment (lp)
00
14
28
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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