Computer OSI and TCP/IP Network Models

Computer OSI and TCP/IP Network Models

1. The computer network model is divided into two types: OSI model and TCP/IP model. Their relationship is as follows:

2. Each layer has its own functions for the OSI model.

1. Application Layer
   The application layer is the closest layer to the user in the OSI model and is responsible for providing network services for your applications. This includes establishing connections between applications or processes that communicate with each other and establishing errors correction and control synchronously. It also contains a large number of application protocols, such as remote Logon (talent), simple mail Transmission Protocol (SMTP), Simple Network Management Protocol (SNMP), and Hypertext Transfer Protocol (HTTP ).
   All programs that support ultrasonic network traffic are at the application layer.

2. Presentation Layer
   The presentation layer is responsible for conversion between different data formats to achieve information exchange between different computer systems. It is also responsible for data encryption, protection during transmission, encryption at the sending end, decryption at the receiving end, and encryption and decryption using the encryption key.

3. Session Layer
   The main function of the Session Layer is to establish connections, maintain, and release user-oriented connections between two nodes, and manage and control sessions to ensure reliable transmission of session data, in the process of session, determine whether to use full duplex or half duplex transmission.

4. Transport Layer
   The transport layer is the only layer in the OSI model responsible for data transmission and control of end-to-end nodes. the transport layer plays an important role in the OSI model. The three layers below it are mainly for network communication, in order to ensure accurate and effective information transmission, the above three-layer tree demon targets host users and provides users with various services.
   In order to provide reliable end-to-end transmission services to the Session Layer, the transport layer also uses Error Control and traffic control mechanisms. Layer-4 protocols include Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Sequential Packet Exchange Protocol (SPX ).

5. Network Layer
   Select the optimal path and plan the IP address (Internet Protocol.

6. Data Link Layer
   The start and end of the data frame. It also provides transparent transmission and error verification.

7. Physical Layer
   Is the bottom layer of the OSI model. It is oriented to the transmission of original bit streams and standardizes interface standards.

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