Instruction manual

CLASS: Calling Number and Name Delivery Page 1107 of 3156
Features and Services
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 Meridian 1 for
internal call setup, traffic on the loop and inter-group junctor should meet
normal GOS requirements, that is 660 CCS per loop or junctor.
If we let an inter-group 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 inter-group 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
traffic flow at junctors, the capacity of a network group in terms of CLASS
sets is summarized in Table 38. The entry in the Table 38 is the threshold for
inter-group junctor traffic check-off.
The table entry indicates that in a two group system, the second group is
allowed to have 1760 CLASS sets or a combination of CLASS and equivalent
sets without a need to move sets or trunks around to reduce inter-group
junctor traffic. Due to higher traffic, an agent set or a trunk is counted to be
equal to four regular sets. The conversion needs to be done before using
Table 38.
If the number of equipped sets (CLASS or otherwise) or equivalent sets (sets
converted from trunks and agent sets) is less than the threshold, the junctor
traffic is expected to be low. There is no special engineering necessary for
CLASS sets (other than providing required modems).
Note that the junctor traffic issue can be ignored if each group is fully
equipped with sufficient CMOD units to handle CLASS sets within the
group. It is the attempt to use one XCMC pack to serve multiple groups that
requires special attention to inter-group traffic. As long as CLASS service is
not impacted by a traffic in-balance already existed in the system, it is not the
objective of this engineering guideline to solve that problem.
Once the threshold is exceeded, re-configuration of the system is necessary to
reduce junctor congestion. The detailed engineering rules are given later in
this document.