Introduction to Computer network (1) system

Review plan

1. Master the basic concepts, basic principles and methods of computer network

2. Master the architecture of computer network and typical network protocols, understand the composition and characteristics of typical network, understand the working principle of typical network equipment

3. Be able to use the basic concept of computer network, fundamental principles and basic methods for the analysis, design and application of networking systems

Learning methods:

Theory + Practice

Protocol Analysis Tool-wireshark

Network topology Tool-packettracer

Secondary command Ping

Tracert (Traceroot)

Computer network architecture and Reference Model

1. Computer network Architecture

Computer network: Through the communication equipment and the line address location different, the function independent multiple computer system interconnection QI, with the function consummation network software (namely communication protocol and so on.) It realizes the system of resource sharing and information transmission in the network.

Network

1) The edge part consists of all the hosts linked on the internet

2) The core component consists of a large number of networks and routers that link these networks

Classification of computer networks

--Wan Wan Wide Area Network

LAN LAN Local Area network

--Metro man Metropolitan area network

--Personal Regional network PAN Personal area Network

Classification from network users

--Public network

--Dedicated network (private network Force public security

Classification by network topological structure

-Star-shaped bus ring tree mesh Line

Standardization work of computer network and related organization

The major organizations that designate communication protocols and standards internationally have the following

1) IEEE LAN, WLAN

2) ISO Network Reference Model

3) ITU

Four phases of standardization

Internet Draft (Internet Draft

--not yet RFC documentation at this stage

Recommended standards (Proprosed standard

--Become an RFC document from the beginning of this phase

Draft standards (Draft standard

Internet standards (Intenet standard

Hierarchical structure of computer network

protocols, interfaces and services in a computer network

The lower layer serves the upper layer, rather than the lower level.

Lower level to provide services for the upper deck!

OSI is a standard

Physical Layer : the communication transmits the original bitstream on the channel.

The key technology is the signal and the interface

link Layer : A technical specification for moving data between adjacent nodes on a network, along a network link. (between adjacent points and points, such as mobile phones to the nearest base station)

The physical layer does not care about the meaning and structure of receiving and transmitting bitstream, but can only rely on each link layer to produce and recognize frame boundaries.

A frame is a unit of information, and each frame should include a certain amount of data and some necessary information

Network layer: Determines whether the packet transmits data from the source to the destination is grouped, that is, a leopard print into the group

The primary is doing routing and forwarding

Transport Layer: receives data from the session layer and divides it into smaller units, if necessary, to the network layer,

Mainly responsible for ... Port number, and so on. (Information to which port the message is forwarded to when it comes to the phone.)

The communication between process and process is realized.

Session Layer: allows users on different machines to create painting relationships, manage conversations, and synchronize. For example, there are easy letter flying Q,

Manage synchronization of sessions and responses.

Presentation layer: It is concerned with the syntax and semantics of application-oriented information. A typical example is the data encoding using a standard method that is uniformly unified by everyone.

Application layer: includes the function that the program executes and the function that the operator performs, in the OSI environment, only the application layer is directly for the user. The application layer includes the most powerful functions, such as the virtual Terminal protocol VTP, e-mail, and so on.

2.TCP/IP model

OSI:HTTPS://ZH.WIKIPEDIA.ORG/WIKI/OSI%E6%A8%A1%E5%9E%8B 1984

TCP/IP:HTTPS://ZH.WIKIPEDIA.ORG/WIKI/TCP/IP%E5%8D%8F%E8%AE%AE%E6%97%8F 1983

The difference is that the application layer is completely simplified, and the three layers are combined in one layer

Introduction to Computer network (1) system