How should we understand network communication protocols? Can we fully master the increasingly complex network structures? We need to rely on network communication protocols for learning and understanding. Network Communication Protocol (Network Communication Protocol )) it is a set of definitions of the Information Format for communication between computers and the transfer content that can be accepted by both parties.
To implement the OSI Layer-7 reference model function, each layer has many communication protocols that are responsible for different aspects and solve different problems, if there are physical interface communication protocols such as RS-232, RS-449 and V.35 in the physical layer), data link protocols such as CSMA/CD, SDLC and HDLC ), the network layer has many routing layer protocols such as IP, RIP, OSPF, and IGRP), while the transport layer has many transmission control protocols such as TCP, FTP, and TFFP ), the Session Layer, presentation layer, and application have many corresponding network protocols, such as POP3, SMTP, SNMP, and DNS at the application layer ). That is, with the combined use of many communication protocols, the layer-7 model of the network can work properly to ensure the normal network communication.
1. Classification of computer network communication protocols
Network protocols are a special software and the most basic mechanism for computer networks to implement their functions. Network protocols are essentially rules that must be followed by a variety of hardware and software. However, the network protocol is not a separate set of software, which is usually integrated into other software systems.
The network protocol covers all layers of the OSI communication model. From the familiar TCP/IP, HTTP, and FTP protocols to OSPF, IGP, and other advanced routing protocols, it can be considered as a network protocol, there are thousands of types.
Among all common network protocols, common basic protocols and common application protocols can also be divided. TCP/IP, ipx spx, and NetBEUI are common basic protocols, while HTTP, PPP, and FTP are common application protocols.
Basic protocols are used to provide network connection services, which are essential for network connection and communication activities. application-oriented protocols are not required for networks, but are only required when they are applied to network services. For example, the HTTP protocol is only required for Internet applications, and the FTP protocol is only used for file transfer activities.
2. functions and composition of computer network communication protocols
The main roles of network protocols and the applicable application environments are different. Some are dedicated. For example, ipx spx is dedicated to the NetWare operating system of Novell, while the NetBEUI protocol is dedicated to Microsoft's Windows systems, and some are general, of course, relative). For example, the tcp ip Protocol applies to almost all systems and application environments.
In so many network protocols, network users only need to master several common and major protocols.
The network protocol consists of three parts: semantics, syntax, and timing.
The meaning of the Protocol elements is interpreted. The semantics defined by different types of protocol elements are different. The syntax is to combine several protocol elements and data to express a complete content format, that is, to define the data structure of information. The time sequence is a detailed description of the event Implementation sequence.
For example, when both parties communicate, a data packet is sent from the sending point. If the target point is correctly received, the source point is correctly received. If an error message is received, the computer network communication protocol requires that the source site be resold once.