Factors that effectthe real-time capacity 109
Service) divided by the number of channels per card. The number of
Follower cards required is affectedby whether the Leader card has
the voice channels enabled or not.
2. Peakednessfactor for call processing is equal to 1.3. This implies that
30% fluctuation is allowed in voice traffic.
3. Callscan terminate or originate on the Leader card. Voice ports are
allowed on the Leader card, depending on configuration foranticipated
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. WhenVAD 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 Network Monitoring
Module.
6. Gatekeeper-routedcalls create a higher load on the card.
7. Thevalues in the tables are valid for all Voice codecs and voice sample
size including G.711, 10 ms voice sample.
Recommendation
Nortel recommends that traffic on a single card Media Card 32-port trunk
card node never exceed the following:
• 4000 calls/hour – Gatekeeper-routed
• 5500 calls/hour – non-Gatekeeper-routed
In a multi-card node, the various roles necessary in processing calls,
such as Leader card, DCHIP card, and Followercard, can be divided
over multiple cards. This ensures that no IP trunk card exceeds its
real-time capacity.
8. Themaximum number of cards one DCHIP card can support is limited
by the restriction of 382 TIE trunks for one D-Channel. Therefore, only
12 Media Cards 32-port or 16 ITG-Pentium 24-port trunk cards can
be supported by one DCHIP card.
Recommendation
Nortel recommends a node never exceed the ratio of 12 Media Card 32-port
trunk cards or 16 ITG-Pentium 24-port trunk cards to one Leader card.
Nortel Communication Server 1000
IP TrunkFundamentals
NN43001-563 02.01 Standard
Release 5.5 21December 2007
Copyright© 2007, Nor tel Networks
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