A computer network is an integrated, a lot of computer, geographically distributed system consisting of interacting local (work) stations and communication subsystem for transmission/ reception of information.
Computer networks are divided into three main types:
- LAN (LocalAreaNetwork – – local area network, which is geographically distributed within one room, office, organization, enterprise;
- MAN (MetropolitanAreaNetwork) – urban or regional network that is geographically distributed within the city, region, etc;
- WAN (WideAreaNetwork) is a global network connecting subscribers of the country, continent, all over the world and geographically distributed over a long distance.
Local computer network (LMB)– represents a set of hardware and algorithms that provide connection of all available computers to the network, sharing of common hardware and software resources, electronic data exchange (information exchange in LMB is carried out using a communication Protocol that meets the relevant standards). Existing standards for coatings provide PC communication at a distance of 2.5 km.
The main purpose of coatings – in the allocation of PC resources: programs, compatibility of peripherals, terminals, memory. So, LMB should have a reliable and fast data transmission system, the cost of which should be less than the cost of workstations connected. That is, the cost per unit of transmitted information should be significantly lower than the cost of information processing in workstations.
Creation of local networks in the organizations functionally provides:
- Equality of network members – means that each subscriber is served on a partnership basis and on the principle of “first come – first served”, which corresponds to the concept of “without the main”;
- Using names on the network – means that each subscriber has its own name on the network, which can be used at the logical level;
- Distribution of access rights – means that the administrator assigns each user or user group local boxes and grants the right to access information in them. Each subscriber should be distributed information only at its level with the appropriate access rights;
- Session maintenance – means that after the names are defined, access rights and permissions are distributed, two network members can connect to each other using the session, which should ensure the quality, speed and reliability of information exchange.