Network protocols - synchronize the operation of computers in the network. The division of protocols into several levels allows the process of data exchange to continue even in the event of any disruptions and failure in the network.
A network protocol is a set of rules that allows two computers connected to a network to establish a connection, exchange all kinds of data with each other, and synchronize the operation of these machines on the network. One specific protocol is responsible for one specific side of the communication type. If you connect them, you can get the so-called protocol stack. In practice, the protocol stack undergoes fragmentation, as a result of which functional levels are formed, each of which has its own specific task.
Protocol stack capabilities
The division of protocols into several conceptual levels made it possible to more quickly and efficiently solve the main tasks of transferring information between several machines. Indeed, at any time, a hardware failure can occur, or one of the devices providing communication, for example, a network card or a hub, can fail. In addition, system or application software may malfunction. An error will occur in the transmitted data itself, part of the transmitted information will be lost or distorted.
The most widely used system of network protocols OSI. It assumes the division of protocols according to their purpose into 7 levels.
Types of protocols
The application or the upper seventh level of the model provides the user with access to network services - the processor of queries to databases, files, mailbox, and others. Negotiates the nuances of transferring service information, notifies applications of errors, and issues requests to the presentation layer.
The presentation layer converts protocols and encodes / decodes data. Converts requests received from the application layer into the most suitable format for transmission over the network. And it converts the response from the network into the format that the applications can understand.
The session layer maintains a session, allowing applications to communicate with each other. To synchronize the transfer, checkpoints are placed in the data stream, which are the starting point for resuming the process in case of any violations.
The transport layer provides data transmission in the order in which it was transmitted. Adjusts the size of data blocks to the protocol.
Network layer - the router determines the shortest route, monitors network problems and congestion.
The data link layer or the data link layer can provide interaction with several physical layers, corrects errors and sends data to the network layer, that is, serves it. Switches and bridges operate at this level.
The physical layer transmits electrical or optical signals to cable or radio, and receives and converts into data bits. Implements the interface between a network device and a network media.
