Page 92 of 378 ITG Engineering Guidelines
553-3001-202 Standard 1.00 April 2000
24-Port ITG Leader and DCHIP Card Real Time Capacit
y
The 24-Port ITG Trunk Card is the NT0961 based on t he Int el P entium C PU.
The 24-Port Leader card real time capa city analysis is as follows. The
following assumptions are made:
1. Average Hold Time (AHT) is equal to 180 seco nds, and traffic per port is
equal to 28 Centi Call Seconds (CCS). This corresponds to a call rate of 15.6
calls per hour.
2. Peakedness factor for call pr ocess ing is equal to 1.3. This impl ies th at 30%
fluctuation is allo w e d in th e voice traffic.
3. Calls can either term i n at e or o rig inate on the Leader card. Voice ports are
allowed on the Leader card.
4. It is also as sumed that when VAD has been en abled in MAT, the voice
fluctuation factor is e qual to 1.5. A v oi ce fl uctua tio n f acto r o f 1 .5 impl ies th at
during a conversation voice is on 50% more tha n the average (in contrast to
silence periods of a conversation). And 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.
It has been determined via me asurements that the Leader ca rd ca n su p po rt
1920 IP ports, all codecs with payload sizes of 10, 20 and 30 milliseconds,
and VAD status equal to “on” with 24 voice ports configured. Under the
above set of assumptions, this corresponds to a total of 53,760 CCS, or 29,867
calls per hour. Note that with 24 voice ports per card, 1920 IP ports
corresponds to 80 Follower cards.
It also supports 1920 IP ports, all codecs with payload sizes of 20 and 30
milliseconds, and VAD when VAD has been disabled in MAT with 24 voice
ports configured. If the payload size is equal t o 1 0 mil liseconds, the number
of supported IP ports, or Follower cards can be determined from Tables 10
and 11. In both tables, 50% voice activity is assume d on the voice ports.
Each Table consists of two cases. Case I assumes that the call mix is 50% call
origination and 50% call terminat ion. Cas e II ass umes th at the ca ll mix i s 0%
call origination and 100% call termination. These two cases are considered
because the call proc essing assis t ti me for o rigi nating call s on th e Lead er ca rd
is negligible, while for the terminating call , this time is non-negligible.