OSI 概念模型

[plh97]

网络为什么要分层

好处在于,每一层只要管好自己的事情就好了, 我们的HTTP协议升级,并不会影响到传输层.各个层相互独立

应用层

chrome浏览器 打开F12,清清楚楚看到所有这一层网络具体干了什么

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Content-Type: text/html; charset=utf-8
Date: Mon, 06 May 2019 15:00:30 GMT
ETag: W/"c5658b08713921e8e372409706d7446a"
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Server: GitHub.com
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(empty)
partial: issues/sidebar/milestone_menu_content

表示层

其实就是基于0信任网络模型构建出来的, 最早的互联网是基于互相信任的模型构建, 因此在不断发展的过程中出现了很多漏洞... 总之表示层具体来说就是类似于https的ssl层加密解密.

会话层

sesstion咯, token咯, 每建立一次网络连接 就相当于建立了会话sesstion, token的cookie写入. 下次免登陆等等.

传输层

它是关于进程与进程之间的通讯,他同时决定了网络流向,向哪个进程委托请求.同时, 我想说,这就像是寄快递, 快递里面的物品是我们寄出, tcp就是快递员,帮我们在快递上面套一层tcp套接层

网络层

ip协议,将一个报文传递给另一个另一个主机

数据链路层

路由器, mac地址交换, 路由器的注册表, 路由器决定应该指向那一台路由作为下一个节点转接.

物理层

铜线,光纤.