7: 1 Station maintenance, operation and administration, telecommunications management network (TMN)

Annotation: The lecture covers all the tasks that are performed by the system to ensure continuous and effective work and optimal use of the installed equipment - maintenance, operation and administration.

General provisions

The term "maintenance, operation and administration" covers all tasks that are performed by the system to ensure continuous and efficient operation and optimal use of the installed equipment.

This system includes the following functions:

1. Administration and operation.
   1. Change subscriber data. This task is to establish and remove additional types of services: the organization and operation of user groups, the detection of malicious calls; maintenance of subscriber, connecting lines and channels - measurement of their parameters, organization of groups of directions; setting restrictions and tracking congestion, setting the interception code for connections for directions along other routes; recording and assigning standard messages to terminals, routing (assigning routes, groups of lines and individual channels).
   2. Traffic measurement Control and adjustment of traffic.
   3. Charging. Installation and adjustment of tariffs. Accounting for the cost of calls.
   4. Ensuring cost documentation. Ensuring the reliability of the cost calculation.
   5. Maintenance of the ACS system. Installation of alarm points. Securing channels for the OKS system. Service user subsystems. Service subsystem management network alarm.
2. Maintenance.
   1. Measurement and testing of subscriber lines.
   2. Measurement and testing of connecting lines and channels.
   3. Diagnosis and repair damage.
   4. Service and maintenance of hardware.
   5. Records of emergency conditions.
   6. Modification and maintenance of reliable software operation.
   7. Modification and maintenance of databases.

Equipment and methods of technical operation and maintenance

As a rule, modern digital PBX does not require the constant presence of attendants. Stations are monitored and maintained through service centers and are visited by operators only during maintenance work. Maintenance systems should provide various organizational forms of service (for example, with specialization of personnel on equipment or universal specialists). When providing a remote interface, a dedicated Q ₃ interface is provided.

The result of such work should be the achievement of a certain quality of functioning of the system.

Error detection and system maintenance are provided by a self-monitoring system, an alarm system, redundancy and failover, as well as the display or printing of information on maintenance terminals.

Diagnostic programs allow the operator to determine the location of the damage and reduce the restoration to the replacement of the element (Type Replacement Element - TEC).

All transactions are documented. To communicate with a person, either the MML (Man Machine Language) recommended by CCITT or the system of typical windows and menus is used. Each message entered is monitored for accuracy and execution is confirmed.

The collected traffic information is subject to special processing. At the same time, data on the busy hour, reports on the quality of service for weeks, months, seasons, etc. are generated. Most often they are presented in the form of graphs, tables, etc.

Each station has an alarm system in the form of display means. Separately, means are provided for testing the measurement of analog and ISDN lines, connecting lines and channels, as well as signaling paths. All these devices can work directly on the start-up team or in the routine maintenance mode. Data can be displayed both on the station panel and on the maintenance center panel.

To test the work with the external environment at the stations, test instruments are provided for testing interfaces and measuring the parameters of lines and channels.

This complex must include:

• testing and measurement of subscriber and connecting lines;
• auto subscriber to establish one and several test compounds at the same time;
• callback device to call the subscriber from the station when repairing it at the location of the user;
• equipment for testing and checking alarms, including long distance and international calls.

Typical maintenance procedure

A typical maintenance procedure is as follows.

1. Alert operator by visual and acoustic means. Visual messages indicate the address and nature of the damage.
2. The operator acknowledges the acceptance of the alarm for maintenance.
3. The operator starts the maintenance procedure on the display.
4. The system leads the operator until the localization of damage.
5. The operator locks the device and runs a diagnostic program that recommends him to a TEC (Typical Element of Replacement).
6. The operator removes the TEC and puts a new one.
7. Testing of the new TEC.
8. A positive test result removes the lock.
9. The station enters the unit into the configuration and informs the operator about the elimination of the failure.

For the repair of a faulty unit, repair centers are organized, which are equipped with special hardware and software. Service is possible to the supplier, then the defective units are sent directly to the company.

Software maintenance

Software maintenance is required to correct errors in the software or in case of deviations in the behavior of the external environment.

In addition, the software may be periodically corrected or upgraded under an agreement with the supplier or due to changes in the network.

To test the software used resident programs or delivered by e-mail and via the Internet manufacturer. This subsystem usually contains software for inserting inserts into existing programs and analyzing time delays when executing procedures put to control, or simply analyzing statistics on the execution time (delays) of programs.

System Reliability Measures

The following principles are used to maintain system reliability:

• Maximum decentralization of call processing.
• Memory structure that is resistant to malfunctions and failures and corrects errors.
• Availability of software backups, preserving the "history" of data changes.
• Reservation equipment.
• Programs of transition to backup equipment and back.
• The system restarts and reboots, when the module starts from the initial position or the software is completely restarted.

There are several recovery levels possible (table 7.1).

Network Support Issues

This topic is related to a large section of the TMN (Telecommunication Management Network) and will be discussed further. In accordance with the TMN concept, the switching system should support a number of centers and workstations, the number and hierarchy of which are determined by the accepted service organization on the network (for example, problem-oriented service groups). In this regard, the station must support the work of operators to perform individual tasks. The powers of the operators must be protected by a personal code, the registration of the users' login and their actions is also carried out.

Documentation

Documentation is important for maintenance and operation.

For instrumental means there are well-tested standards and well-known documents - manuals on technical operation and maintenance. For stations using software, the practice is still ahead of standardization. For effective operation, the following software descriptions are needed:

• at the specification level (specification - description of the list of tasks performed by the software);
• at the description level (description is a description of what the software consists of and how it is made).

Appropriate guidelines should be drawn up, accompanied by algorithms for the main sections: Administration and maintenance; Exploitation.

A software documentation system based on ITU recommendations is reviewed in [12].