OSI : Open systems Interconnection 开放系统互联,由ISO定义的互联网模型(Internet model),分为七层
7,Application Layer
provide user interface to internet
http,ftp,dns,telnet...
6,Presentation Layer
Code and encode,compress and uncropress
5,Session Layer
estblishment and termination of a link
4,Transportation Layer
end to end
3,Network layer
router choose, error and flow control
ip address
2,Data Link Layer
Frame of data
MAC address
1,Physics Layer
To transfer data between different physics media
MAC(Media Ascess Control)由48bit组成,具有全球唯一性
ARP协议用来将IP映射到MAC地址
交换机工作在数据链路层