What is the OSI model

The OSI model is an open system interconnection communication reference model. It is a conceptual model proposed by the International Organization for Standardization. It is a standard framework that attempts to interconnect various computers into networks around the world.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

What is the OSI model?

Open System Interconnection Reference Model (English: Open System Interconnection Reference Model, abbreviated as OSI), referred to as OSI model (OSI model), a conceptual model proposed by the International Organization for Standardization. A standard framework that attempts to interconnect various computers into networks around the world. Defined in ISO/IEC 7498-1.

Level division

According to recommendation X.200, OSI divides the computer network architecture into the following seven layers, labeled 1 to 7, with layer 1 at the bottom. Now "OSI/RM" is the abbreviation of "Open Systems Interconnection Reference Model" in English.

• Layer 7 Application Layer

Main entry: Application layer

Application Layer provides application software An interface designed to set up communication with another application software. For example: HTTP, HTTPS, FTP, TELNET, SSH, SMTP, POP3, etc.

• The 6th layer of presentation layer

Main article: Presentation layer

The presentation layer (Presentation Layer) converts the data into A format that is compatible with the recipient's system format and suitable for transmission.

• Layer 5 Session Layer

Main entry: Session Layer

The Session Layer is responsible for data transmission Sets up and maintains communication connections between two computers in a computer network.

• Layer 4 Transport Layer

Main entry: Transport layer

Transport Layer (Transport Layer) puts the transport header (TH) is added to the data to form a packet. The transmission header contains sending information such as the protocol used. For example: Transmission Control Protocol (TCP), etc.

• Layer 3 Network Layer

Main entry: Network Layer

The Network Layer determines the path of data Select and forward, adding a network header (NH) to the packet to form a packet. The network header contains network data. For example: Internet Protocol (IP), etc.

• Layer 2 Data Link Layer

Main article: Data Link Layer

Data Link Layer Link Layer) is responsible for network addressing, error detection and error correction. Frames are formed when headers and trailers are added to the packet. The data link header (DLH) contains the physical address and error detection and correction methods. The Data Linked List (DLT) is a string indicating the end of the packet. Examples include Ethernet, Wireless LAN (Wi-Fi), and General Packet Radio Service (GPRS).

It is divided into two sub-layers: logical link control (LLC) sub-layer and media access control (MAC) sub-layer.

• Layer 1 Physical Layer

Main entry: Physical Layer

Physical Layer (Physical Layer) is uploaded on the local LAN Send data frame (data frame), which is responsible for managing the intercommunication between computer communication equipment and network media. Includes pinouts, voltages, cable specifications, hubs, repeaters, network cards, host adapters, and more.

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