Nortel Networks NN43001-563 - Manual (Page 104)

104 ITG engineering guidelines
Factors that effect the real-time capacity
The following factors affect real-time capacity:
• host module type
• the number of ports configured on the Leader card, codec selection,
and voice sample size
• size of the IP Trunk 3.01 (and later) network
• endpoint type
• the Average Hold Time (AHT) and distribution of incoming calls
Host module type
The Media Card 32-port trunk card has a significant real-time advantage
for already-established calls; therefore, the Media Card 32-port trunk
card supports more ports then the ITG-Pentium 24-port trunk card. The
ITG-Pentium card has an advantage in the processing of call setup
messages.
Additionally, other factors, such as the number of QoS endpoints being
monitored, have a greater effect on the Media Card 32-port trunk card.
In most applications, these differences have no effect on a customer
configuration.
The number of ports configured on the Leader card, codec selection,
and voice sample size
The number of voice ports configured on an IP trunk card can reduce the
card’s ability to fulfil other roles, such as the Leader card or DCHIP card. In
large networks or large nodes, it might be necessary to disable some or all
of the voice ports on an IP trunk card.
The more bandwidth a voice codec and voice sample size requires, the
more packets are sent and received. For example, using the G.711 voice
codec with a 10ms payload results in more packets being generated than
other codecs generate. The extra packets use some of the IP trunk card’s
real-time capacity. This would only become a concern if the IP trunk card
is a Leader or DCHIP card. Disabling the voice ports on an IP trunk card
has a greater benefit in terms of saving real-time capacity than using a
lower bandwidth codec.
Size of the IP Trunk 3.01 (and later) network
If QoS is enabled on an IP Trunk 3.01 (and later) network, the size of the
network has a direct impact on the real-time capabilities of an IP trunk
Leader card and on single card nodes.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.