【TCP/IP】Network Model

【TCP/IP】网络模型

1.作用

实现网络通信

2.总体概览

3.Introduction to each layer

1.应用层

最上层的,dealing with users(That is, the application software we can touch is implemented in the application layer)

应用层为用户提供的功能:

Eg:HTTP,FTP,TELNET,DNS,SMTP

注意:The application layer does not care how the data is transmitted,就像你想寄快递,Just give your express package to the courier,这个包裹就相当于数据,怎么送,你不关心,That's a courier thing

2.传输层

This transport layer is equivalent快递员,Transport application layer data packets,对应用层Provides network support

应用层>>>传输层>>>应用层

传输层的两个协议:TCP和UDP

TCP: 传输控制协议

最大的特点:保证可靠传输

UDP:

It is a name佛系,Just simple send数据报,There is no guarantee that the datagram will arrive,但是效率很高(Like you call a courier:The courier delivered quickly,But it does not guarantee that the package you give will work100%送到目的地.)

The origin of the port:

当设备作为接收方时,system to transmit数据包sent to the application,But a device may have很多应用receiving or transmitting data,需要一个编号Separate applications,这个编号就是端口

For Example:

1.web端口通常是80端口

2.22端口通常是远程登录服务器用的

3.Our usual browser,We open a new one every time标签栏,The system will create a temporary for them端口号(Because each process is one独立的进程)

3.网络层

举个例子:

包裹交给快递员,快递员how to deliver目的地,这个过程,采用飞机?大炮,车车?等等,This process is done by the network layer(Not too strict!!),

​ 嗯…你想想快递系统,快递系统决定Where does the courier go,perform the tasks of that stage,这个快递系统就是相当于网络层===哼哼哈嘿!!!

IP协议:

这是网络层最重要的协议(相当于The courier company's shipping express运输工具)

IP报文:将传输层的报文作为数据部分,再加上IP包组成IP报文

IP分片:一般是IP报文超过MTU(The specified bytes of general Ethernet are 1500字节),就会将IP报文Perform sharding operations.

IP地址

就是相当于我们的快递单号

组成:网络号+主机号

1.网络号:负责标识该IP地址属于那个子网的

2.主机号:Responsible for uniformity of identification子网下面的不同主机

网络号&How to calculate host number?

IP地址与子网掩码按位与运算:

比如 10.100.122.0/24,后面的/24表示就是 255.255.255.0 子网掩码,进行按位与的运算得到网络号

The same operation is performed to invert the subnet mask,然后与IP地址进行按位与的运算,可以得到主机号

IP路由:

就是相当于快递中转站

IP寻址

Tell us where to go next,Like the equivalent of a navigation system.

4.网络接口层

This can be understood as the courier who really rides your courier on the road小摩托in transport

最重要的MAC帧