Computer networks: basic characteristics, classification and principles of organization

There is practically no modern mankindrepresents his life without computers, and yet they did not appear long ago. Over the past twenty years, computers have become an integral part of all areas of activity: from office to educational needs, thereby creating the need to develop the capabilities of computers and develop related software.

The combination of computers in the network allowedonly increase productivity, but also 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 isthe "client-server" principle. In this case, the client is an architectural component that uses the server's capabilities with the help of a login and password. The server, in turn, provides its resources to other network members. This can be storage, the creation of a common database, the use of I / O, etc.

There are several types of computer networks:

- local;

- regional;

- Global.

Here it is fair to note on what principles different computer networks are built.

Organization of local computer networks

Typically, such networks unite people who areat a short distance, so they are most often used 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 diagram 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. Star - the connection in which the nodes are raysconnect with the center. This model of connection has gone from those distant times when computers were quite large and only the head machine received and processed information.

As for global networks, then everything is much more complicated. To date, there are more than 200. 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.