Nortel ISDN Signaling Link, Описание, установка и эксплуатация

Страница: 143 / 380

ITG Engineering Guidelines Page 143 of 378
ITG Trunk 2.0 ISDN Signaling Link (ISL) Description, Installation and Operation
Estimate QoS level
You can use Table 24 to estimate the IP telephony QoS level based on QoS
measurements of the intranet. To limit the size of this table, the packet loss
and one-way delay values are tabulated in increments of 1% and 10ms
respectively. The techniques used to determine and apply the information in
this table are Nortel Networks proprietary.
Table 24
ITG QoS levels (Part 1 of 4)
Packet
loss (%)
One-way
delay (ms)
QoS level
G.729A G.711A/G.711u G.723.1
0 50-200 excellent excellent excellent
0 210-220 excellent excellent good
0 230-330 good excellent good
0 340-360 good good good
0 370-380 good good fair
0 390-620 fair good fair
0 630-780 fair fair fair
0 790 fair fair poor
1 50-180 excellent excellent good
1 190-200 good excellent good
1 210-320 good good good
1 330-340 good good fair
Note: The QoS levels are equivalent to the following MOS values: (See page 56 for more details)
• excellent 5
• good 4
• fair 3
• poor 2