A computer network is nothing more than a combination of several computers among themselves, allowing them to exchange data. Global networks are called when they reach users from all over the world. Note that the first civilian computer networks appeared in the United States. But few people know that the very principle of this technology was first used in the USSR, and thanks to this, the first missile defense system was once created long ago.
Today there is a fairly broad classification of networks. By territorial prevalence distinguish global, local and regional computer networks. Global computer networks are networks located on the territory of a state or several states, for example, the Internet. Local networks cover the territory up to several tens of square meters, and regional networks are networks that are located in the region or city.
However, the two main terms in the classification of networks are: WAN and LAN.
WideAreaNetwork (WAN) - global computer networks covering large regions, which include local area networks and other telecommunications devices and networks.
LocalAreaNetwork (LAN) - Local area networks that have a closed infrastructure before they reach service providers. The very term “LAN” is able to describe both a small office network and the network of a large plant, which covers an area of several hundred hectares.
The oldest global network is the Internet. It provides various ways of connecting remote computers and sharing information resources and distributed services.
Initially, global computer networks were engaged in solving the problem of accessing various remote terminals and computers to powerful computers called hosts. These connections were made using non- switched or switched channels of telephone networks or using dedicated satellite data networks, for example, operating under the X.25 protocol.
To connect to such networks, modems were used that worked under the control of specialized telecommunication programs, such as COMIT, PROCOM, BITCOM, MITEZ, etc. Managed by MS-DOS, they exchanged information with the computer to which the connection was established.
The very construction of a global network It’s not difficult to describe. The global network consists of cells, which are local area networks. In turn, local networks consist of smaller networks and individual computers. This multilevel hierarchy provides network building. In addition, each device on the network must have its own IP address or unique identifier.
Nowadays, single computers that are part of global computer networks are increasingly being used. Basically, these are home PCs. For the most part, network subscribers are those computers that are included in local area networks, therefore, most often, specialists are working out options on how best to ensure the interaction of several local area networks at once. At the same time, it is necessary to ensure that the remote computer has a connection with any computer included in the remote local network, or vice versa. The latter option is very relevant when increasing the number of home and personal computers.
Nowadays, switching centers are used as network equipment, which are specialized devices for manufacturers of Telenet, Ericsson, Siemens, Alcatel, etc. for X.25 networks, but they use Decnis and Cisco routers for networks with TCP / IP. However, technology does not stand still, and it is likely that in the future we will see an even more effective organization of the global network, which today has a huge impact on the lives of almost every person.