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Foreword:
A network protocol is a set of rules, standards or conventions established for data exchange in a computer network. For example, if a microcomputer user communicates with a mainframe operator in the network, since the two data terminals use different character sets , the commands entered by the operators do not know each other. In order to be able to communicate, it is stipulated that each terminal must first convert the characters in its own character set into characters in the standard character set before entering the network for transmission, and after reaching the destination terminal, convert them into characters in the terminal character set. Of course, for incompatible terminals, other features need to be converted in addition to character set characters, such as display format, line length, number of lines, and screen scrolling methods.
1. Introduction to network protocols
A protocol is a term used to describe the rules for exchanging data between processes (see "Law" for a definition of "protocol"). In a computer network, two entities that communicate with each other are located in different geographical locations , and the two processes on them communicate with each other. They need to coordinate their actions to achieve synchronization by exchanging information, and the exchange of information must be in accordance with a pre-agreed agreement. The rules are carried out.
2. Elements of network protocol
- Semantics: Semantics is the interpretation of the meaning of each part of the control information. It specifies what kind of control information needs to be sent, as well as the completed action and what kind of response to make.
- Syntax : Syntax is the structure and format of user data and control information, and the order in which the data appears.
- Timing: Timing is a detailed specification of the sequence in which events occur. (Also called "synchronization").
- People vividly describe these three elements as: Semantics means what to do, grammar means how to do it, timing means the order of doing.
3. Network protocol hierarchy
Due to the complexity of the connection between network nodes, when formulating a protocol, the complex components are usually decomposed into some simple components, and then they are combined. The most commonly used composite technology is the hierarchical method. The hierarchical structure of the network protocol is as follows:
- Each layer in the structure specifies clear service and interface standards.
- Put the user's application as the top layer
- Except for the highest layer, each layer in the middle provides services to the layer above, and at the same time is a user of the layer below.
- Taking the physical communication line as the lowest layer, it uses the parameters transmitted from the highest layer and is the basis for providing services.
Four. Hierarchy
In order to enable computers produced by different computer manufacturers to communicate with each other so as to establish a computer network on a larger scale, the International Organization for Standardization ( ISO ) proposed the "Open System Interconnection Reference Model" in 1978, the famous OSI/RM model ( Open System Interconnection/Reference Model). It divides the communication protocol of the computer network architecture into seven layers, from bottom to top: Physical Layer, Data Link Layer, Network Layer, Transport Layer ), session layer (Session Layer), presentation layer (Presentation Layer), application layer (Application Layer).
5. Commonly used protocols
TCP/IP protocol
It is undoubtedly the most important of the three major protocols. As the basic protocol of the Internet, it is impossible to surf the Internet without it. Any operation related to the Internet is inseparable from the TCP/IP protocol. However, the TCP/IP protocol is also the most troublesome to configure among the three major protocols. It is okay to surf the Internet on a single computer, but to access the Internet through a LAN, it is necessary to set the IP address, gateway, subnet mask, DNS server and other parameters in detail .
Although TCP/IP is the most popular network protocol at present, the communication efficiency of TCP/IP protocol in the local area network is not high. When using it to browse computers in "My Network Places ", normal browsing often occurs. Installing the NetBEUI protocol at this time will solve this problem.
NetBEUI
That is, NetBios Enhanced User Interface, or NetBios Enhanced User Interface. It is an enhanced version of the NetBIOS protocol, which has been adopted by many operating systems, such as Windows for Workgroup, Win 9x series, Windows NT, etc. The NETBEUI protocol is useful in many situations and is the default protocol for operating systems before WINDOWS98. The NetBEUI protocol is a short, compact, and highly efficient broadcast protocol. It does not need to be set up after installation, and it is especially suitable for transmitting data in "Network Neighborhood". Therefore, it is suggested that in addition to the TCP/IP protocol, the computers in the small LAN can also install the NetBEUI protocol. Another point to note is that if a WINDOWS98 machine with only TCP/IP protocol installed wants to join the WINNT domain, the NetBEUI protocol must also be installed.
IPX/SPX protocol
It was originally a protocol developed by Novell for use in NetWare networks, but it is also very commonly used now-most online games support the IPX/SPX protocol, such as StarCraft, Counter-Strike, and so on . Although these games can also be connected online through the TCP/IP protocol, it is obviously more convenient to use the IPX/SPX protocol because no settings are required at all. In addition, the IPX/SPX protocol does not seem to be very useful in the local area network. If you are sure not to play games online in the local area network, then this protocol is dispensable.
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