The purpose of this series of articles is to “give every front-end engineer a high frequency knowledge base to help with their work”. This is the 33rd cut of the front hundred questions. I hope friends will pay attention to the public number “kite holder” and arm their minds with knowledge.
Network architecture has a variety of partitioning standards: OSI architecture, TCP/IP architecture, and five-layer protocol architecture. Among them, OSI architecture is the most finely divided architecture, and other TCP/IP architecture and five-layer protocol architecture are obtained by aggregating some layers of OSI architecture. The above three structures are divided as follows:
The TCP/IP architecture and the five-tier protocol architecture are based on the OSI architecture by some level of aggregation, so we will focus on the OSI architecture of the function of each layer.
- The physical layer
The physical layer is the first layer. Its main function is to use the transmission medium to provide physical connection for the data link layer and realize the transparent transmission of bit streams, so that each bit in the frame can be moved from one node to the next. (Raw bitstream transmission on mechanical, electronic and timing interface communication channels)
- Data link layer
The data link layer is responsible for establishing and managing links between nodes. This layer is responsible for moving entire frames from one network element to adjacent network elements. (Physical addressing and converting the original bitstream to a logical transmission line)
- The network layer
The network layer is responsible for moving network layer groups called datagrams from one host to another. This layer includes the well-known Internet protocol IP, which defines the various fields in the datagram and how the end system and router act on them. (Control the operation of subnets, such as logical addressing, packet transmission, routing)
- The transport layer
The transport layer is responsible for providing universal data transmission services for the communication between two host processes, mainly using TCP and UDP protocols. (Receive the data from the session layer, divide the data if necessary, and send the data to the network layer, and ensure that the data segment reaches the peer end effectively)
- The session layer
The session layer is the interface between the user application and the network. Its main task is to provide the means to establish and consume the connection to the presentation layer of the two entities. (Establish and manage sessions between users on different machines)
- The presentation layer
The presentation layer interprets the commands and data from the application layer, assigns corresponding meanings to 袯, and transmits them to the session layer according to a certain format. The presentation layer mainly handles the presentation of user information, such as encoding, data format conversion, encryption and decryption. (Syntax and semantics of information and their associations, such as encryption and decryption, transformation and translation, compression and decompression)
- The application layer
The application layer is the interface between various applications and the network. It directly provides services to users and performs various tasks desired by users on the network. Common protocols include HTTP, HTTPS, FTP, and SSH. (Various application protocols, such as HTTP, FTP, SMTP, POP3)
Note: to view published to company network protocol figure (www.colasoft.com.cn/download/ne)…
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