Linux operation and Maintenance Network Foundation

I. Definition of computer network

What is a network?

A group of computer systems with independent functions are interconnected by communication devices and transmission media, and the whole system of resource sharing and information exchange is realized with the support of communication software.

The basic condition of generating computer network: The combination of communication technology and computer technology

Second, the emergence and development of computer network

1954 host-terminal communication network first generation computer network

A single host-centric, end-device-oriented network structure. In addition to the independent data processing function of the main computer in the system, the terminal equipment connected in the system does not have the function of independent processing.

1969 Host-host communication network ARPANET Network second generation computer network

the computer network with packet switching network as the center, the communication both sides of the network are the computers with the ability of autonomous processing, and the function is based on resource sharing.

Packet switching is divided into multiple fragments called packets (packet), each packet carrying address information independent transmission, through the communication node processor for storage and forwarding, each communication node processor according to the destination address of the packet carrying, using routing algorithm to select the forwarding path, The packet forwarding from the source node to the destination node is completed by point.

1983 Network OSI model of architecture standardization third generation computer network

Open Systems Interconnection Reference Model

the establishment of the Internet fourth generation computer network

Third, the composition of computer network

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M02/72/E1/wKioL1XvphyxAghXAAB_B0b60GQ415.jpg "title=" E0bf5ba4f007d563e5830a7b3f687baf.jpg "alt=" Wkiol1xvphyxaghxaab_b0b60gq415.jpg "/>

from the point of view of network logic function, computer network can be divided into two parts, communication subnet and resource subnet.

The network system is centered on the communication subnet, and the communication subnet is in the inner layer of the network, which consists of communication devices, communication lines and computers used only for information exchange, which is responsible for completing the network data transmission, forwarding, processing tasks,

The current communication subnet is typically made up of routers, switches, and communication lines

The resources subnet is in the periphery of the network, has the host system, the terminal, the terminal controller, the peripheral, the various software resources and the information resources composition, is responsible for the entire Network data processing service, provides the network user various network resources and the Network service.

Iv. functions of the computer network

data communication: Realizing the exchange of information between computer and computer

resource sharing: sharing hardware, software, and data resources to provide resource utilization

improve the reliability of your computer: make your computer A backup machine through network settings and prevent server failures from causing the network to fail

easy to distribute: combine multiple computers into a high-performance computer system to accomplish a complex task together

V. Classification of computer networks

1. Classification by geographical coverage

LAN: IEEE802 series Standard

Metropolitan Area Network: More as a backbone network

Wan:

Internet:

2, according to the Network Exchange way classification

Circuit Switching network: Before the user begins to communicate, the first step is to establish a physical channel from the sending end to the receiving end, and always occupy the channel during the communication between the two parties.

Message Exchange Network: The data to be sent and the directory address is contained in a complete message, the length of the message is unrestricted. The message exchange adopts the principle of storage-forwarding, each intermediate node chooses the appropriate path for the passing message, so that it can reach the destination end.

Packet switching network: Before the communication, the sending side first divides the data to be sent into a unit of equal length (that is, grouping), which is transmitted by each intermediary node by means of storage-forwarding, and finally arrives at the destination end.

3. Topological structure of computer network

General line topology structure

Ring-type topological structure

STAR topological structure:

Tree-type topological structure

Network-based topologies:

Linux Operations Network Fundamentals