Computers communicate with each other over short distances, or on a single network segment or lan.
物理层和数据链路层,保证了电脑传输信息,
于短距离、局域网,可用
allow data to across many networks, facilitating communications to over great distances.
跨越多网络的通信,
远距离的通信
subnetting 子网划分
routing 路由
局域网的搞法:
Lan , nodes ( client / server ) can communicate through their physical mac addresses, this works well on small scale, because switches ( hub ) can quickly learn their mac addresses , connected to each other's ports. to perform transmissions properly .
Mac addresses , 他是唯一的,但是他没有什么规律,
基于 Mac addresses 远距离通信,不合适
通过 ARP 协议,解决距离问题
Address Resolution Protocol
32 位 IP v 4:
dotted decimal notation
点分十进制表示法
8 位,2 的 8 次方,最大 127
0 ~ 127
IP 地址,属于网络
the device has an IP address assigned to it
-
自动获取 IP 的协议,
Dynamic Host Configuration Protocol
动态主机配置协议
产生
Dynamic IP Address
-
还存在 Static IP Address
客户端,一个动态 IP 就好了
服务器和网络设备,使用静态 IP
网络层,The Network Layer
数据包和封装, IP Datagram and Encapsulation
IP 层, 一个数据包 ,是一个数据报 datagram
IP 层的包头 datagram header ,比 Ethernet 层的 frame header, 数据更加丰富
最上方,4 bytes , Version