A communication protocol is a rule and convention that must be followed by an entity to complete a communication or service. A plurality of data communication systems of different geographical locations interconnected by communication channels and devices must have a common language between them in order to enable them to work together for information exchange and resource sharing. What to communicate, how to communicate, and when to communicate must follow certain mutually acceptable rules. This rule is the communication protocol. Grammar: How to communicate, including the format of the data, the encoding and the signal level (level of the level). Semantics: communication content, including data content, meaning, and control information. Timing rules (timing): When to communicate, clarify the order of communication, rate matching, and ordering. 1.TCP/IP The history of TCP/IP (Transport Control Protocol/Internet Protocol) should be traced back to the predecessor of the Internet, the ARPAnet era. In order to achieve interconnection between different networks, the US Department of Defense developed the TCP/IP architecture and protocol from 1977 to 1979. TCP/IP is a combination of a set of sub-protocols with professional use, including TCP, IP, UDP, ARP, ICMP, and so on. TCP/IP has rapidly developed due to its low implementation cost, secure communication between multiple platforms, and routable connectivity, and has become the standard protocol in the Internet. In the 1990s, TCP/IP has become the preferred protocol in LANs, and TCP/IP has been the default communication protocol installed in the latest operating systems (such as Windows 7, Windows XP, Windows Server 2003, etc.). 2.NetBEUI protocol The NetBEUI (NetBIOS Enhanced User Interface) protocol is developed by NetBIOS (Network Basic Input Output System), which requires simple configuration and less network resource consumption, and can provide very good error correction. It is a A fast and efficient protocol. However, due to its limited network node support (up to 254 nodes) and non-routing, it is only suitable for small LANs based on Windows operating systems. 3.IPX/SPX protocol The IPX/SPX (Internet Packet Switching/Sequence Packet Switching) protocol is mainly used in Novell LANs based on the NetWare operating system. LANs based on other operating systems (such as Windows Server 2003) can communicate with the Novell network through the IPX/SPX protocol. In the Windows 2000/XP/2003 system, the IPX/SPX protocol and the NetBEUI protocol are collectively referred to as NWLink. 1. Divide the communication function into several levels, each part completes some functions, and each level cooperates with each other to complete the communication function. 2. Each layer only interacts with two directly adjacent layers. It uses the functions provided by the next layer to provide the higher layer with the services that this layer can perform. 3. Each layer is independent, and the compartments can be implemented using the most suitable technology. Each level can be developed and tested separately. When a layer of technological progress changes, as long as the interface relationship remains the same, the other layers are not affected. The hierarchical structure is shown in the figure below. Each layer implements a relatively independent function, the lower layer provides services to the upper layer, and the upper layer is the user of the lower layer, and each layer cooperates with each other to complete the communication function. Protocol hierarchy diagram Layering the network system is to decompose the complex communication network coordination problems and then separately process them to simplify the complex problems, so as to facilitate the understanding of the network and the design and implementation of each part. The protocol is only for a certain layer, and is designed for communication between peer entities. It is easy to implement and maintain, has good flexibility, and is structurally separable. The data communication protocol Data communicaTIon protocol is also known as the data communication control protocol. It is a series of conventions prescribed to ensure effective and reliable communication between the two parties in the data communication network. These conventions include the format, order and rate of data, confirmation or rejection of data transmission, error detection, retransmission control and interrogation. There are two types of data communication protocols: one is called basic communication control protocol, which is used for data transmission based on characters, such as BSC protocol (binary synchronous synchronous communication protocol); the other is called advanced key control protocol. Used for bit-based data transmission, such as HDLC (Advanced Data Link Control Protocol) and SDLC (Synchronous Data Key Control Protocol). The basic protocol is used in a simple low-speed communication system, the transmission speed is generally not more than 9600 bps, and the communication is asynchronous/synchronous half-duplex mode. The error control is the policy code. The advanced key control protocol adopts a unified frame format with high reliability, high efficiency and high transparency, and is widely used in public data networks and computer networks. The transmission rate is generally between 2.4 kbps and 64 kbps, the communication is continuously transmitted in a synchronous full-duplex mode, and the error control is a cyclic redundancy code check.
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Data communication protocol type analysis
What is a communication protocol?