ITG Engineering Guidelines Page 117 of 378
ITG Trunk 2.0 ISDN Signaling Link (ISL) Description, Installation and Operation
Table 20 provides a sample measurement of network delay and packet loss
for the G.729A codec between various nodes.
Table 20
Sample Measurement Results for G.729A codec
As an example, the delay an d l o ss pair of traffic from Santa Clara to
Richardson (171 ms and 1.5%) will meet “excellent” criterion, but their
counter part with standard deviation (179 ms and 2.1%) can achieve only
“good” QoS.
Since the algorithm implemented in ITG will calculate mean only and not
standard deviation, it will confirm the “excellent ” rating (if the objective is
set for excellen t, it will not fal lback to alter nate facilities ), but the custom er
will have up to 50% chance to experience a service level inferior to
“excellent” level.
As a contrast, the site pair Santa Clara/Ottawa which has both QoS levels of
mean and mean+σ falling i n the excellent re gion. The customer will have
more confidence that (better than 84% chance under the assumption of
Normal distribution) during peak traffic period, the “excellent” service level
is likely to be upheld.
Destination pair Measured One way
delay (ms)
Measured Packet
loss (%)
Expected QoS level
(See page 143)
Mean Mean+σMean Mean+σMean Mean+σ
Santa Clara/
Richardson 171 179 1.5 2.1 Excellent Good
Santa Clara/
Ottawa 120 132 1.3 1.6 Excellent Excellent
Santa Clara/
Tok yo 190 210 2.1 2.3 Good Good
Richardson/
Ottawa 220 235 2.4 2.7 Good Good
Richardson/
Tok yo 305 345 2.2 2.6 Good Fair
Ottawa/
Tok yo 260 286 2.4 2.8 Good Fair