Computer networks: basic characteristics, classification and principles of organization

Modern mankind practically does not represent its life without computers, and in fact they appeared not too long ago. Over the past twenty years, computers have become an integral part of all areas of activity: from office to education, thereby creating the need to develop the capabilities of computer technology and develop related software.

The combination of computers in the network allowed not only to increase labor productivity, but also to reduce the cost of their maintenance, as well as reduce the time of data transfer. In other words, computer networks have two goals: sharing software and hardware, and providing open access to data resources.

The construction of computer networks is based on the principle of "client-server". In this case, the client is an architectural component that uses the server's capabilities with a login and password. The server, in turn, provides its resources to other network members. This can be storage, creating a common database, using I / O, etc.

There are several types of computer networks:

- local;

- regional;

- Global.

It is fair to note on which principles different computer networks are built .

Organization of local computer networks

Usually such networks unite people who are at a close distance, that is why they are used most often in offices and enterprises for storing and processing data, transferring its results to other participants.

There is such a thing as "network topology". Simply put, this is a geometric scheme of combining computers into a network. There are dozens of such schemes, but we will consider only the basic ones: a tire, a ring, and a star.

1. A bus is a communication channel that connects nodes to a network. Each node can receive information at any convenient moment, and transmit - only if the bus is free.
2. Ring. With this topology, the working nodes are connected in a series in a circle, that is, the first station is connected to the second and so on, and the latter is connected to the first, thereby closing the ring. The main drawback of such an architecture is that if the work of at least one element fails, the entire network is paralyzed.
3. A star is a connection in which nodes are connected to the center by rays. This model of connection has gone from those remote times when computers were quite large and only the head machine received and processed information.

As for global networks, everything is much more complicated. Today there are more than 200 of them. The most famous of them is the Internet.

Their main difference from local ones is the lack of a basic management center.

Such computer networks work on two principles:

- server programs located on the nodes of the network that deal with user maintenance;

- client programs located on user PCs and using server services.

Global networks give users access to various services. You can connect to such networks in two ways: through a dial-up telephone line and through a dedicated channel.