Modern mankind can hardly imagine its life without computers, but they appeared not so long ago. Over the past twenty years, computers have become an integral part of all areas of activity: from office needs to educational ones, thereby creating the need to develop the capabilities of computer technology and develop related software.
The combination of computers in a network has 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, as well as providing open access to data resources.
The construction of computer networks is based on the principle of “client-server”. At the same time, the client is an architectural component that uses the capabilities of the server with the login and password. The server, in turn, provides its resources to the rest of the network. This can be storage, creating a common database, using I / O, etc.
Computer networks come in several forms:
- local;
- regional;
- global.
It will be fair to note here on what principles various computer networks are built .
Organization of local computer networks
Typically, such networks bring together people at close range, therefore they are used most often in offices and enterprises to store and process data, and transfer its results to other participants.
There is such a thing as a network topology. Simply put, this is a geometric diagram of a network of computers. There are dozens of such schemes, but we will only consider the basic ones: a tire, a ring, and a star.
- A bus is a communication channel that connects nodes to a network. Each of the nodes can receive information at any convenient moment, and transmit it only if the bus is free.
- Ring. With this topology, the working nodes are connected in series in a circle, that is, the first station is connected to the second and so on, and the last is connected to the first, thereby closing the ring. The main drawback of this architecture is that if at least one element fails, the entire network is paralyzed.
- A star is a connection in which the nodes are connected by a beam to the center. This connection model dates back to those far times when computers were quite large and only the host machine received and processed information.
As for global networks, then 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 the local ones is the absence of a main management center.
Such computer networks carry out work on two principles:
- server programs hosted on network nodes that deal with user services;
- 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.