Nortel Networks NN43001-563 - Manual (Page 134)

134 ITG engineering guidelines
Serialization delay
Serialization delay is the time it takes to transmit the voice packet one bit at
a time over a WAN link. The serialization delay depends on the voice packet
size and the link bandwidth, and is calculated using the following formula:
Serialization delay in ms = 8 * (IP packet size in bytes)/(link bandwidth in
kbit/s)
Table 27 "Serialization delay" (page 134) shows what the serialization delay
for voice packets on a 64 kbit/s and 128 kbit/s link. The serialization delay
on higher speed links are considered negligible.
Table 27
Serialization delay
Codec
Frame
duration
Serialization
delay over
64 kbit/s link
(ms)
Serialization
delay over
128 kbit/s link
(ms)
10 ms 14.00 0.88
20 ms 24.00 1.50
G.711A/
G.711U
30 ms 34.00 2.13
10 ms 5.25 0.33
20 ms 6.50 0.41
G.729A/
G.729AB
30 ms 7.75 0.48
G.723.1 5.3
kbit/s
30 ms 6.50 0.41
G.723.1 6.3
kbit/s
30 ms 7.00 0.44
Queuing delay
Queueing delay is the time it takes for a packet to wait in transmission queue
of the link before it is serialized. On a link where packets are processed in
first-come-first-serve order, the average queueing time in ms is estimated by
the following formula:
p*p*(average intranet packet in bytes)/(1-p)/(link speed in kbit/s)
where p is the link utilization level.
The average size of intranet packets carried over WAN links generally is
between 250 and 500 bytes.
Figure 26 "Queuing delay of various links"
(page 135) displays the average queueing delay of the network based on a
300-byte average packet size.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.