Telecommunication network and its components
The term telecommunications comes from the Greek tele - far, far away and Latin communico - I do the general, connect. It can be treated as a communication at a distance. Therefore, by telecommunication network we mean a set of facilities that provide information transfer between two terminal devices (subscribers). The network includes:
• network equipment, which includes endpoints (personal computers, servers, audio and video devices, network printers, fax machines, bar code readers, etc.) and communication equipment (wire, cable and/wireless media, as well as intermediate devices such as network adapters, modems, repeaters, bridges, switches, etc.);
• Tools for supporting network equipment. In such a complex system as a telecommunications network, you need to have a wider arsenal of software, as well as standard sets (stacks) of communication protocols that define rules for the interaction of network devices.
Telecommunications network structure
The telecommunications network has a hierarchical structure (Figure 9.1), reflecting the traffic intensity between its individual nodes located in different buildings, settlements and regions. The nodes of the network are switches, representing multiport devices,
Fig. 9.1. Generalized structure of the telecommunications network
to which the communication lines are connected. Let's consider separate components of a telecommunication network.
Terminal devices users are located on the periphery of the telecommunications network and constitute the lowest level of its hierarchy. Usually the type of such devices determines the name of the network. The main terminal devices in a computer network are computers, telephone - telephone sets, television - television receivers, in the radio network - radio receivers.
Information from users on subscriber channels, often called subscriber endings, goes to the access network switches.
The access network represents the next level of the hierarchy of the telecommunications network. A large such network can consist of several levels. The main functions of the access network are:
• in the aggregation or multiplexing of information streams coming from multiple user devices into one common stream and transferring the aggregated stream to the backbone switchboard
• in receiving and dividing or demultiplexing the aggregated stream into separate streams so that only the information addressed to the user's input port receives information addressed to it.
Backbone network is intended for the transit of aggregated information flows from the senders' access network to the recipient access network. It contains switches and high-speed communication links (backbones).
The information center , or the service management center, is designed to provide information services to users (subscribers) of the network. Everyone knows the information services of the Internet, as well as telephone networks (getting help information, calling an ambulance and the police) and cellular networks (televoting).
Note that each telecommunications network has its own peculiarities, for example: there are no information centers in small telephone and computer networks; The access network and the backbone of the local computer network can be represented by cable segments; the access network of the broadcasting and television networks perform only distribution functions, since the information in them is transmitted in one direction (towards the subscribers).