The basic concept of network is the relationship among services, protocols, processes and ports.

The router is an essential device in network communication , Because with the development of network demand , Whether it's a business IDC Routers are required for network connections in the computer room or in the home of ordinary users , So I will describe the working principle of the router here , This is generally for enterprises IDC Description in the machine room , The router in the user's home is also a gateway device that communicates with the Internet , Because there is no need to divide subnets in the user's home .

Router

Equipment responsible for connecting different subnets , It can realize cross subnet communication

Communication rules

Outgoing subnet communication , You must find a gateway , The gateway is the interface of the subnet router

Communication within the same subnet , No gateway

Same as subnet , Same as segment , That is, hosts in the same subnet ,IP The address must be in the same network segment （IP The first three paragraphs of are the same ）; Hosts of different subnets ,IP Segments cannot be the same        

              

Basic concepts of network

agreement ：

Rules and agreements that both parties to the communication must abide by , Such as ：http、ftp、DHCP、DNS

code ：

Text during transmission 、 Pictures and other data information , How to convert to binary , The conversion rule is called encoding         english ：ASCII    chinese ：UTF-8、gb2312 

service ：

A network function is called a service , Such as ： Web browsing , be called web service ; File downloads are called ftp service       The implementation of the service must comply with the agreement

      Identity after computer networking

            The server

                serviceable

            client

                    Use 、 Access to the service

process ：

In order to realize the service , The program that runs is called a process .

      The service process complies with the agreement

      Running the service process on the server ; The client runs the client process ; The essence of communication is the connection and communication between two processes

      Extended concept

          Program ： Stored on disk , Software that doesn't work

          process ： Put in memory 、CPU in , Running programs , Called process

          Threads ： A step-by-step process , It's a thread

port ：

It is used to distinguish different processes in the host , Number the process , This number is port Port number

          function ： distinguish 、 Identify process