Network Delay And Packet Loss Evaluation Example - Nortel 1000 Description, Installation And Operation Manual

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Network delay and packet loss evaluation example

Table 29
Sample measurement results for G.729A codec (Part 1 of 2)
Destination
pair
Santa Clara/
Richardson
Santa Clara/
Ottawa
553-3001-363 Standard 2.00
ITG engineering guidelines
Late packets
Packets that arrived outside of the window allowed by the jitter buffer are
discarded by IP Trunk 3.01 (and later). To determine which PING samples to
ignore, first calculate the average one-way delay based on all the samples.
Add 500 ms to the average. This is the maximum delay. All samples whose
one-way delay exceeds this maximum are considered late packets and
removed from the sample. Calculate the percentage of late packets and add
that to the packet loss statistic.
From PING data, calculate the average one-way delay (halved from PING
output and adding 93 ms IP Trunk 3.01 (and later) processing delay) and
standard deviation for latency. Do a similar calculation for packet loss
without adjustment.
Adding a standard deviation to the mean of both delay and loss is for planning
purposes. A customer might want to know whether traffic fluctuation in their
intranet reduces the user's QoS.
Table 29 provides a sample measurement of network delay and packet loss
for the G.729A codec between various nodes.
Measured one-way
delay (ms)
Mean Mean+σ
171 179
120 132
September 2004
Measured
Packet loss
(%)
Mean Mean+σ
1.5 2.1
1.3 1.6
Expected QoS level
(See page 201)
Mean Mean+σ
Excellent Good
Excellent Excellent