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1 Reference
Reference book information:
- "Graphic TCP/IP (5th Edition)", P11;
2 Summary of knowledge points notes
1. "Computer Network Architecture" systematically summarizes these network protocols. TCP/IP is a collection of protocols such as IP, TCP, and HTTP.
2. Various network architectures and protocols
| Network architecture | protocol | The main purpose |
|---|---|---|
| TCP/IP | IP，ICMP，TCP，UDP，HTTP，TELNET，SNMP，SMTP… | Internet, local area network |
| IPX/SPX（NetWare） | IPX，SPX，NPC… | Personal computer local area network |
| AppleTalk | DDP，RTMP，AEP，ATP，ZIP… | Local area network of Apple's existing products |
| DECnet | DPR，NSP，SCP… | Former DEC minicomputer |
| OSI | Ftam moved VT, CMIS / CMIP, CLNP, drawer ... | —— |
| XNS（Xerox Network Services） | IDP，SPP，PEP… | Xerox Network |
3. Agreement is like a dialogue between people
To give an example, ABC three people, A can only speak Chinese, B can only speak English, and C can speak both Chinese and English;
- Treat Chinese and English as "agreement";
- Treat chat as "communication";
- Treat the content of speech as "data";
4. Packet exchange protocol
Packet switching refers to a method of dividing big data into smaller units called packets for transmission.
(1) The written part of these sender address, receiver address and packet sequence number is called "message header".
(2) When a larger data is divided into multiple packets, in order to indicate which part of the original data is, it is necessary to write the serial number of the packet into the packet. The receiving end will reassemble each packet into the original data according to the serial number according to this serial number.
(3) In the communication protocol, it is usually specified what information should be written in the header of the message, and how to handle this information.
(4) Each computer that communicates with each other constructs the message header and reads the content of the header according to the protocol. In order for the two parties to communicate correctly, the sender and receiver of the packet must maintain consistent definitions and interpretations of the message header and content.
3 Problem summary record
1. What is the difference between CPU and OS? What's the difference?
CPU (Central Processing Unit) is translated as central processing unit. It is like the "heart" of the same computer, and each program is actually scheduled for execution. The performance of the CPU largely determines the processing performance of a computer. Therefore, it is often said that the development history of computers is actually the development history of CPUs.
At present, the commonly used CPUs include Intel Core, Intel Atom, and ARM Cortex.
OS (Operating System) is translated as operating system and is a kind of basic software. It integrates important functions such as CPU management, memory management, computer peripheral device management, and program operation management. The processing of TCP or IP protocol introduced in this book is actually embedded in the specific operating system in many cases. Operating systems commonly used in personal computers today include UNIX, Windows, Mac OS, Linux, and so on.
The instructions that can be run in a computer vary depending on its CPU and operating system. Therefore, if a program designed for some specific CPU or operating system is directly copied to a computer with another type of CPU or operating system, it may not be able to run directly. The data stored in the computer also differs depending on the CPU and operating system. Therefore, if communication is realized between CPUs and computers with different operating systems, a protocol supported by all parties is required, and data reading is performed in accordance with this protocol.
In addition, a CPU can usually only run one program at the same time. In order to allow multiple programs to run at the same time, the operating system uses the CPU time slice rotation mechanism to switch between multiple programs for reasonable scheduling. This method is called multi-task scheduling. The realization of the time-sharing system mentioned in the previous section 1.2.2 actually uses this method.
4 summary
- A brief understanding of "computer network architecture";
- Understand briefly what is a packet switching protocol;
- Have a brief understanding of what CPU and OS are and what is the difference;
- Make a little progress every day, come on!
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