Layered learning network communication protocol

As a modern network, we divide it into seven levels for learning. The Protocol content varies with different levels. Now let's take a look at the relevant network communication protocols. First, let's take a look at what network communication protocols are.

◆ Introduction

All parts of communication must agree with a set of rules for information exchange) A set of protocols that specify the Message format and the appropriate actions required for each message are known as the network protocol (networkprotocol) or the computer communication protocol (communicationprotocol) software that implements these rules is called protocol software (protocolsoft) the protocol that specifies the format and meaning of messages in computer information exchange is called the communication protocol. This paper analyzes the architecture and application of the computer network protocol, at the same time, the use of C language to achieve TCP and UDP transmission process. Finally, let's look forward to the future development of network protocols ｡

◆ Brief introduction to computer network communication

Network protocol design generally assumes that the protocol participants are completely obedient, complete a specific task according to the provisions of the protocol. All parts of the communication must agree with a set of rules for information exchange) this term can also be used for computer communication (a set of protocols that specify the Message format and the appropriate actions required for each message are known as the network protocol (networkprotocol) or the computer communication protocol (communicationprotocol )) the software that implements these rules is called protocol software (protocolsoft). A protocol that defines the format and meaning of messages in computer information exchange is called a communication protocol ｡

◆ Network communication protocols and their roles

In computer network technology, communication procedures are generally referred to as protocols. A protocol is a series of agreements that people make in advance when designing a computer network system, the communication protocol used by the computer network is complex. The Protocol consists of three parts: syntax, semantics, and exchange rules. Semantics is the content to be expressed by both parties, that is, the elements contained in the Protocol. The syntax specifies the representation of these elements. That is, the format exchange rules of elements in the Protocol refer to the response relationship between these elements, that is, the rules for changing the status of data communication. The data is sent from the source station in the computer network to the receiving of the destination station, and finally to the dialogue or interoperability between the receiving and sending sides, requires a series of protocol operations ｡

For example, the sending station sends data to the line according to the destination address, first, it must be transmitted over the link. The link is a path unit that ensures error-free transmission between communication nodes. After each node receives the information, it performs error detection and correction, and then send it to the next node. If an error cannot be corrected, the destination address includes the network segment number of the destination station and the Node Address of the node on the network segment, if there are multiple network branch paths on an intermediate node, in order to make the information transmitted in the most economical and fast path, the intermediate node must have broken the route, then, it is possible to transmit the data from the sending station to the receiving station across multiple networks and send the data to the destination station ｡

After that, end-to-end error verification and correction may also be required. The connection between processes, languages, or Code Conversion between computer programs in the interaction between receiving and sending sites, finally, the application layer is reached to process the information of the application. After the communication is completed, the connection should be removed to release the channel, strict protocols are required for each stage ｡

◆ Network communication protocol layering and functions

According to the recommendations of the International Organization for Standardization (ISO), the currently widely used network structure model is the Open System Interconnection Model (OSI). This is a layer-7 protocol, including the physical layer protocol, data link layer protocol, network layer protocol, transport layer protocol, Session Layer Protocol, presentation layer protocol, and application layer protocol ｡

The physical layer protocol implements transparent transmission of Inter-bit stream information between physically connected systems, that is, the reliable transmission and communication of one-bit (Group) data between two communication entities, it describes the establishment, maintenance, and removal of physical connections between data link entities through the communication media. The data link layer protocol is mainly used to shield the transmission media at the high level, provides network communication entities with functions and means to establish, maintain, and release data link connections, implements reliable transmission of error-free data in frames. The Network Layer Protocol provides interface connections between the Communication Subnet and the high-level structure. Its main task is to select the path for the Communication Subnet, it implements transparent data transmission between communication entities, blocking the path of data transmission at the top ｡

The Transport Layer Protocol, also known as the host-host layer protocol, provides transparent data transmission between communication entities at the Session Layer. Its main task is to receive data sent by session entities, divide them into several smaller units as needed to ensure that all data units reach another session entity through the following three layers. The Session Layer Protocol is also called the process-process layer protocol, it uses a set of commands provided by the Protocol to establish a session connection and release a session connection for communication between two processes on the Internet, and manage their conversations on the connection. The presentation layer protocol provides information representation services in a meaningful form for the Application entity. These services include text compression, code conversion, data encryption and decryption ､ file Format Conversion, information format conversion, terminal attribute conversion, etc. The application layer protocol is the interface layer for users to access the network, directly serves the application process of the end user who is communicating. Therefore, these are all the Protocol content in the big concept of network communication protocol.