The concept of a computer network implies the following definition of it. A network is a collection of objects that is formed by devices that transmit and process data. The International Organization for Standardization defines a computer network as a sequential bit-oriented system for transmitting information between independent, but in a special way interconnected devices.
The architecture of computer networks is such that networks usually occupy a certain territory, so they are most often divided according to territorial characteristics. There are local, regional and global networks.
The advantages provided by the network association of personal computers most often include the possibility of sharing resources, sharing data, sharing software, sharing processor resources, the ability to organize a multi-user mode.
Various signs of networks make it possible to create various classifications of computer networks. These signs include the topology of computer networks, their purpose, the list of services provided, management principles (can be centralized and decentralized), switching methods, access methods, types of transmission media, data transfer speed , etc.
Let us dwell in more detail on such an important concept as the topology of computer networks. In any computer network, each workstation is physically connected to other communication channels. The connection is carried out according to a certain structure, which is called the topology of computer networks. Thus, the topology of computer networks is inherently a description of physical connections in a computer network, which indicates specific workstations that can communicate with each other. The type of computer network topology is characterized by the type that determines the level of productivity, operability and reliability of operation of workstations integrated into the network, as well as the time period required to access the file server. In addition, the topology directly affects the network access method that will be applied.
To date, there are five varieties of computer network topologies, but three are widely used: bus topology, ring topology, star topology .
The bus topology assumes that all network nodes will be connected to a peer- to -peer network using a single cable. The end of the cable should be a resistive load. A single cable supports a single data channel . In bus topology, a cable is called a bus. Networks built according to bus topology are created on the basis of coaxial cable.
Ring topology has found its implementation in simple peer-to-peer computing networks. All workstations, according to this topology, are connected to their two closest neighbors. If you look at the general connection diagram in a network created by a ring topology, you can see something resembling a ring. Data in such networks can be transmitted in a single direction, and all workstations work as repeaters that receive and respond to packets addressed to them, and then transmit the remaining data packets to the next workstation, which is located “downstream”.
The most widespread today are local networks built according to star topology. In such networks, data to devices diverge from a common point represented by a hub, router, or switch. If you imagine a hub as the center of a star, then the divergent from it will resemble the rays - hence this topology got its name. The main advantage of a star-shaped topology in comparison with a ring topology is the possibility of realizing the right of independent access to the network provided to any device. In this case, each device is able to access the transmission medium, regardless of other devices located on the network.