Nortel Networks NN43001-563 User Manual

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ITG engineering guidelines

In this section, the following assumptions are made to project the Leader
Card real-time capacity:

•

The number of probe packets per Leader Card is 25.

•

If the average hold time is 180 seconds, the number of calls per hour
per port is 15.3 calls.

•

If the average hold time is 10 seconds, the number of calls per hour per
port is 187.5 calls.

•

50% of the calls are incoming and 50% are outgoing.

ITG-Pentium 24-Port trunk card Leader 0 and DCHIP card
real-time capacity

The ITG-Pentium 24-port trunk card is based on the Intel Pentium CPU. The
real-time capacity analysis of the ITG-Pentium 24-port trunk card Leader 0
is as follows. The following assumptions are made:

1. The minimum number of Follower cards required is a function of the call

rate (which is limited by the Leader and DCHIP card) and the Average
Hold Time (AHT) (which is a function of the number of channels per
card). The number of Follower cards is calculated by the number of
voice channels required (using Poisson 1 percent blocking Grade of
Service) divided by the number of channels per card. The number of
Follower cards required is affected by whether the Leader card has
the voice channels enabled or not.

2. Peakedness factor for call processing is equal to 1.3. This implies that

30% fluctuation is allowed in the voice traffic.

3. Calls can terminate or originate on the Leader card. Voice ports are

allowed on the Leader card, depending on configuration for anticipated
traffic. Enabling the voice ports on a Leader or DCHIP card decreases
the number of Follower cards required by one card, but can substantially
affect the amount of traffic that can be handled for that node.

4. When VAD has been enabled in TM 3.1, the voice fluctuation factor

is equal to 1.5. A voice fluctuation factor of 1.5 implies that, during a
conversation, voice is on 50% more than the average, in contrast to
silence periods of a conversation. With VAD status equal to "off", the
voice fluctuation factor is equal to 1.1.

5. 15% of CPU real-time has been reserved for the Network Monitoring

Module.

6. Gatekeeper-routed calls create a higher load on the card.

7. The values in the tables are valid for all Voice codecs and voice sample

size including G.711, 10 ms voice sample.

Nortel Communication Server 1000

IP Trunk Fundamentals

NN43001-563

01.01

Standard

Release 5.0

30 May 2007