Network basics

Network basics

First, the background of the emergence of computer networks

Independent mode to interconnect mode. Initially, the computer stand-alone mode (independent mode) was widely used, and slowly developed into a mode of connecting computers together to realize information sharing between computers to form a computer network (local area network, wide area network).

The computer network formed by the initial administrator connecting several computers (the same company, laboratory) is a private network. As the private network continues to develop, multiple private networks are connected to form a larger private network. Gradually evolved into the Internet for public use.

Second, the seven stages of computer and network development

2.1, Batch Processing System (Batch Processing)

In the 1950s, people began to use transistors instead of vacuum tubes to make computers, which greatly reduced the size of computers, significantly reduced power consumption, and greatly improved reliability, so that computers have the value of popularization and application, but computer systems still very expensive. In order to make full use of the computer, the system should be run continuously, the idle time should be reduced, and a batch processing system should appear. (not interactive, just to improve CPU utilization)

Batch processing means that after the user submits a batch of jobs to the operating system, they no longer intervene, and the operating system controls them to run automatically. A batch of operations (programs and data) is stored in advance on the tape, and a supervised program is placed on the system. Under the supervision of the program, the batch of operations is successively processed one by one.

2.2, Time Sharing System

The time-sharing system that emerged in the 1960s, the time-sharing system refers to connecting multiple terminals with a display and a keyboard on one host, while allowing multiple users to use the computer in an interactive manner through the terminal, sharing the host. Resources. A time-sharing system is a circuit connection between a computer and a terminal, which does not mean that a connection is formed between the computer and the computer.

2.3, communication between computers

In the 1970s, before the implementation of inter-computer communication technology, data exchange between two computers was realized by an external storage medium (tape, etc.), which was very cumbersome. As computers become smaller and cheaper, companies are beginning to use computers to handle their business. To improve productivity, people are beginning to study communication technologies between computers.

2.4, computer network generation

In the early 1970s, people began experimenting with computer networks based on packet switching technology and studied communication technologies between computers of different vendors. In the 1980s, a network that could connect computers from multiple vendors was born, from large computers to small personal computers, which allowed a wide variety of computers to connect to each other.

2.5, the popularity of the Internet

In the 1990s, information dissemination methods such as e-mail and e-mail, the World Wide Web WWW, developed rapidly, and the Internet has grown widely from large companies to small families.

2.6. The era centered on Internet technology

The popularity and development of the Internet have had a huge impact on the communications field. After 2000, with the replacement of the telephone network by IP networks, the devices that can be networked are not only computers but also extended to mobile phones, household appliances, game consoles, and other equipment.

2.7, from "simple connection" to "safe connection"

The Internet has brought a highly convenient network information environment to people, and it also brings many negative effects (virus violations, information disclosure, etc.) to people. People are no longer satisfied with the "simple connection" in the early days of Internet popularization. More pursuit of the goal of "safe connection."

Third, the agreement and protocol layering (OSI reference model)

Protocol: A pre-agreed agreement between computers when communicating over a network; this convention enables communication between devices manufactured by different vendors, computers with different CPUs, and different operating systems, as long as the same protocol is followed. (The two computers must be able to support the same protocol and follow the same protocol for communication.)

Network basics

First, the background of the emergence of computer networks

Independent mode to interconnect mode. Initially, the computer stand-alone mode (independent mode) was widely used, and slowly developed into a mode of connecting computers together to realize information sharing between computers to form a computer network (local area network, wide area network).

The computer network formed by the initial administrator connecting several computers (the same company, laboratory) is a private network. As the private network continues to develop, multiple private networks are connected to form a larger private network. Gradually evolved into the Internet for public use.

Second, the seven stages of computer and network development

2.1, Batch Processing System (Batch Processing)

In the 1950s, people began to use transistors instead of vacuum tubes to make computers, which greatly reduced the size of computers, significantly reduced power consumption, and greatly improved reliability, so that computers have the value of popularization and application, but computer systems still very expensive. In order to make full use of the computer, the system should be run continuously, the idle time should be reduced, and a batch processing system should appear. (not interactive, just to improve CPU utilization)

Batch processing means that after the user submits a batch of jobs to the operating system, they no longer intervene, and the operating system controls them to run automatically. A batch of operations (programs and data) is stored in advance on the tape, and a supervised program is placed on the system. Under the supervision of the program, the batch of operations is successively processed one by one.

2.2, Time Sharing System

The time-sharing system that emerged in the 1960s, the time-sharing system refers to connecting multiple terminals with a display and a keyboard on one host, while allowing multiple users to use the computer in an interactive manner through the terminal, sharing the host. Resources. A time-sharing system is a circuit connection between a computer and a terminal, which does not mean that a connection is formed between the computer and the computer.

2.3, communication between computers

In the 1970s, before the implementation of inter-computer communication technology, data exchange between two computers was realized by an external storage medium (tape, etc.), which was very cumbersome. As computers become smaller and cheaper, companies are beginning to use computers to handle their business. To improve productivity, people are beginning to study communication technologies between computers.

2.4, computer network generation

In the early 1970s, people began experimenting with computer networks based on packet switching technology and studied communication technologies between computers of different vendors. In the 1980s, a network that could connect computers from multiple vendors was born, from large computers to small personal computers, which allowed a wide variety of computers to connect to each other.

2.5, the popularity of the Internet

In the 1990s, information dissemination methods such as e-mail and e-mail, the World Wide Web WWW, developed rapidly, and the Internet has grown widely from large companies to small families.

2.6. The era centered on Internet technology

The popularity and development of the Internet have had a huge impact on the communications field. After 2000, with the replacement of the telephone network by IP networks, the devices that can be networked are not only computers but also extended to mobile phones, household appliances, game consoles, and other equipment.

2.7, from "simple connection" to "safe connection"

The Internet has brought a highly convenient network information environment to people, and it also brings many negative effects (virus violations, information disclosure, etc.) to people. People are no longer satisfied with the "simple connection" in the early days of Internet popularization. More pursuit of the goal of "safe connection."

Third, the agreement and protocol layering (OSI reference model)

Protocol: A pre-agreed agreement between computers when communicating over a network; this convention enables communication between devices manufactured by different vendors, computers with different CPUs, and different operating systems, as long as the same protocol is followed. (The two computers must be able to support the same protocol and follow the same protocol for communication.)