All CO digital exchange equipment requiring direct current shall be designed to operate at a nominal -48 Vdc. The power system shall have sufficient capacity to serve the common control equipment, the number of lines, trunks and the traffic specified for each exchange. Batteries, rectifiers, dc power control, and dc and ac distribution equipment (including standby diesel generators) shall be included.
Power Supply Requirements for Digital Exchange Equipment
For power supply telecommunication equipment’s specifications, refer to the various applicable documents, and to the following Saudi Aramco’s standards, and materials system specifications:
SAES-K-511 Diesel Engines
SAES-P-100 Basic Power System Design Criteria
SAES-P-103 Direct Current and UPS Systems
SAES-T-151 Communication D.C. Power System
17-SAMSS-511 Stationary Storage Batteries
17-SAMSS-514 Battery Charger/Rectifier
17-SAMSS-518 Diesel Generators
5.42 Network Management
Networks, which are engineered to handle a normal traffic load, can quickly become overloaded when there is an unusual increase in subscriber calling or loss of capacity, or both. Network management is the function of supervising these networks, on a real-time basis, and taking action to control the flow of traffic. This shall ensure the maximum utilization of network capacity in all situations.
ITU-T E.410 shall be met. In additions, observance shall be made of current amendments.
The objective of network management requires a “systems” approach which looks not only at the performance of individual network components but also the performance of the network as a whole. Thus, it shall be possible for the new exchange(s) on all levels in the network (local, combined, transit, and international exchanges) to provide basic network management functions as recommended by ITU-T. These functions shall be designed for local and/or centralized network management, covering the following areas:
a) Network performance information and reporting.
b) Network management controls.
The network management functions shall be designed to suit various structures of network management organization and level of operation.
Local and/or central staffing and operation with central operation is understood to be the operation of a number of exchanges from one center like the Saudi Aramco Network Operation Control Center (NOCC) facilities in Dhahran. The NOCC facility shall be upgraded in order to incorporate constant changes within the Saudi Aramco network, necessary for the expansion, upgrade and/or replacement of any existing equipment in the network. In the case of central operation it shall still be possible in failure situations to perform network management activities from a back-up point.
5.42.2 Preparations for Future Requirements
The functions provided, by the digital exchange, shall be prepared for smooth conversion to future automatic network management on a broad basis. This regards both the information part and the traffic flow control part of the functions. The preparations shall include possibilities for common channel signaling systems, i.e., ITU-T Recommendation Signaling System Number 7, to be used for carrying network management signals.
5.42.3 Network Performance Information and Reporting
To meet the requirements for local and/or central operation, a number of network performance information and reporting functions shall be provided by each exchange. The following information, as a minimum, is required:
a) Call attempt rate and traffic on each incoming route and for the whole exchange.
b) Grade of service of local and trunk calls that is being achieved.
c) Proportion of calls which are delayed beyond the stated limit.
d) Traffic and call attempt rate on outgoing trunk groups.
e) All Trunk Buses (ATBs) occurrences and durations.
f) Any action that the system has taken, in response to its call processing program, to reduce its traffic load.
5.42.4 Network Management Controls
Ordinary traffic routing follows a preprogrammed fixed routing pattern, normally an “alternative routing” program. This routing copes with standard dimensioned traffic load fluctuations. Network management controls temporarily override the ordinary routing to regulate abnormal traffic flows. It shall be possible to administer the network management controls in a uniform and effective way to meet network management objectives.
Consideration shall be taken to guarantee safe temporary routing changes by authorized personnel.
The control shall be able to operate on:
(a) Traffic resources through percentage control, i.e., restriction or addition of accessible circuits.
(b) Outgoing traffic flow through percentage control (blocking a percentage of calls) or call gap control (minimum time interval between transmitted calls).
It shall be possible to direct rejected calls to special recorded announcements advising subscribers (and operators) to take appropriate actions.