Done by: Mardonov B

Done by: Mardonov B.

• Topic: Definition of layers, services, interface and protocols

Plan:

• The concept of an open system
• Open Systems Interconnection Model
• Interfaces and Services
• Service Primitives
• Protocol
• Seven-level modelOSI

The concept of an open system
Definition. A system that meets the requirements of ISO standards is called an open system.
The theoretical basis of modern information networks is determined by Basic reference model of the International Standards Organization (ISO)-standardISO 7498.
THIS ISfundamentalsamethodology for organizing the interaction of application processesIreceived in various network nodes.
Ореn System Interconnection - OSI
All tasks that need to be solved to organize interaction between information system objects are divided into seven separate procedures or levels
When developing the OSI reference model standard, the following tasks were solved:

• unification of the description of the operation of a separate system;
• defining an interface for information exchange between systems;
• unifycationdata exchange between different information systems;
• removal of technical barriers to communication systems

Model OSI - layered architecture principle
In the OSI model, several layers of protocols form the so-called
stackprotocols, in which each protocol operates at its own level

• all network functions are divided into levels,whichinteractbetween themselvesvia interface
• twhich layered structure allows you to modify and even replace any level without affecting all the others
• division into levels makes it possible to simplify the implementation of each of them as much as possible.

Level structure of the model OSI