Modern humanity practically cannot 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 needs, thereby creating a need to develop the capabilities of computing technology and develop related software.
Combining computers into a network allowed not only to increase labor productivity, but also to reduce the cost of their maintenance, as well as to reduce the time of data transfer. In other words, computer networks serve two purposes: the sharing of software and hardware, and the provision of open access to data resources.
Computer networks are built according to the "client-server" principle. At the same time, the client is an architectural component that, using the login and password, uses the capabilities of the server. The server, in turn, provides its resources to the rest of the network participants. This could be storage, creating a shared database, using I/O facilities, etc.
Computer networks come in several forms:
Here it is fair to note the principles on which various computer networks are built.
Organization of local computer networks
Usually, such networks unite people who are at close distance, therefore they are most often used in offices and enterprises for storing and processing data, transmitting its results to other participants.
There is such a thing as "network topology". Simply put, it is a geometric scheme for connecting computers to a network. There are dozens of such schemes, but we will consider only the basic ones: bus, ring and star.
- A bus is a communication channel that connects nodes into a network. Each of the nodes can receive information at any convenient moment, and transmit only if the bus is free.
- Ring. With this topology, the work nodes are connected in series in a circle, that is, the first station is connected to the second, and so on, and the last one is connected to the first, thereby closing the ring. The main drawback of this architecture is that if even one element fails, the entire network is paralyzed.
- Star - a connection in which the nodes are connected by rays to the center. This connection model has come from those distant times, when computers were quite large and only the host machine received and processed information.
As for globalnetworks, then everything is much more complicated. To date, 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 the main management center.
Such computer networks work according to two principles:
- server programs hosted on network nodes that are engaged in user service;
- client programs hosted on user PCs and using server services.
Global networks give users access to various services. There are two ways to connect to such networks: through a switched telephone line and through a dedicated channel.