OSI Network Model

The team of specialists in 1978 developed the OSI standard. The network model OSI considered is not an individual network standard. It is a network template with a certain number of levels, on which all standardized systems are designed. This model determines the types of operations on the network that are offered by different standards. The seven-level OSI network model is, we might say, the "standard of standards". The levels of this model are discussed below.

1. Physical

This network layer of the OSI model is the lowest step. It is responsible for the physical properties of the network, namely: the type of cable, the length of the cable, the type of connectors that are used to communicate devices, etc. Among other things, this level is responsible for the electrical parameters of the signals that the system uses to transfer data between nodes in the network. A conventional binary system is used to designate signals : 0, 1.

2. The link layer

The stage at which the information bits are assigned the set values is called the OSI network layer. Standards of this level should include data on the size of each of the data packets being sent, on the means of addressing them, which allow the packet to be sent to the desired recipient, and how to remove data from multiple nodes simultaneously. It also protects the system from errors.

3. OSI Network Model: Network layer

A network layer is responsible for securing the connection of networks using the routing of information packets between systems. When working with it, you do not need to think about the differences in standards during the connection of systems on the channel and physical levels.

4. OSI Network Model: Transport Layer

Ensures the joint work of two computers on the network. Its function includes assigning each computer an individual address and managing the connection between nodes.

5. OSI Network Model: session layer

This level serves to enable you to create a communication session between different nodes. He is responsible for synchronizing tasks that are running on different computers. To do this, it creates checkpoints that allow you to not send all the data a second time when receiving an error, but to repeat the transfer of information from the control point, from which the error was detected.

6. OSI Network Model: presentation layer

This level is responsible for converting the information transmitted in the network from one type of format to another. This level has the ability to encrypt the data when forwarding, as well as decrypt it when it is received by the desired node.

7. Application layer

OSI Network Model It has the highest step - the application layer, which provides the connection of application programs with the network system. In simple terms, he is responsible for accessing programs on the network. On the basis of the application layer, programs are run that provide access to the Internet (browsers), allow data exchange (FTP clients and servers), exchange electronic messages ( e- mail clients), and so on.