Nortel 1000 Features And Services Fundamentals page 502

502 CLASS: Calling Number and Name Delivery
The CND information of a traffic source (A) is a system information, which is
obtained by the system when a call is originated. During the two-second
ringing period of the CLASS set B, A's CND is delivered to CMOD through
SSD messages (using a signaling channel only). When the CND information
is sent from CMOD to CLASS set B, it is delivered through a voice path
during the four-second silence cycle of set B. The CMOD unit is held for
a duration of six seconds.
If the XCMC (Extended CLASS Modem Card) IPE pack, which provides
up to 32 CMOD units, is located in the IPE of Group 0, the CMOD unit in
the pack will receive CND data through the SSD messages and use one
of the voice channels of the intergroup junctor to deliver it to CLASS set B
in Group 1.
If the XCMC IPE pack is located in Group 1, the system will deliver SSD
messages containing CND information to CMOD and then send it to Set
B during the delivery interval through a voice path, which is an intragroup
channel not involving an intergroup junctor.
When CMOD units and CLASS sets are co-located in the same network
group, there are no voice paths on the intergroup junctor required to deliver
CND information; when they are equipped on different groups, intergroup
junctors must carry CND traffic. The resource allocation algorithm will
search for a CMOD unit located in the same group as the terminating
CLASS set first before it attempts to use a CMOD unit from a different group.
Intergroup junctor capacity
The time slot allocation algorithm for intergroup junctors is somewhat
different from regular network loops, however, it is a close approximation to
use the network loop capacity for junctor capacity, since they each have 30
traffic channels.
In order for the connection between a CMOD unit and the remote set (on
a different group) to meet the Grade Of Service (GOS) of the system for
internal call setup, traffic on the loop and intergroup junctor should meet
normal GOS requirements, that is 660 CCS per loop or junctor.
If we let an intergroup junctor be loaded to 660 CCS like a loop, the total
allowed traffic at eight junctors is 5280 CCS (=660x8). At 6 CCS per
CLASS set, the allowed number of sets generating intergroup traffic is 880
(=5280/6). If half of set traffic is intra-group, and the other half inter-group,
the allowed number of CLASS sets in Group 1 is 1,760 (=880/0.5). On per
loop basis, each loop can be equipped with 62 (=1760/28) CLASS sets.
Similarly, a 3-group network is likely to have 1/3 of traffic remaining in the
group, 1/3 of traffic going to the next group, and another 1/3 of calls going
to the third group. By using this inverse proportion approach to breakdown
Copyright © 1994–2008, Nortel Networks
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Nortel Communication Server 1000
Features and Services Fundamentals — Book 2 of 6 (C)
NN43001-106 02.04 Standard
Release 5.5 9 May 2008