ISO seven layer model
Physical layer: transmission, a physical interface, cable and other electrical characteristics of the bitstream between the device (electrical characteristics: total cable, line 8 with 1,3,2,6 only four wires used to transmit data over five now. class interface or so), the network card.
Data Link Layer: Framing (framing head to write in a data packet source and destination MAC addresses), media access, the error detection and correction MAC address of
the network layer: providing a logical address (IP address is written, a source and the IP destination), the routing (path selection through which the transmission data - routing path) of
the transport layer: reliable and unreliable transmission, before the transmission error detection, flow control (flow control). Determining whether reliable transmission protocol (the TCP: Transmission Control Protocol reliable, data transfer must not lost; the UDP: User Datagram Protocol faster, but may lose data) is used to determine the port number (port number of the sending and receiving)
Session Layer: application session management, synchronization (controls whether to forward to the transport layer, if this operation is mail forwarded to the transport layer, the file is not stored in the local forwarding)
layer representation: representation of the data (the application layer -> session layer: the presentation layer 0101 characters into machine language form, session layer -> application layer, is converted into human-readable language characters), specific functions such as - encryption, compression.
Application Layer: a user interface
名称 传输协议 传输单元 主要功能设备/接口
物理层 IEEE 802.1A、IEEE 802.2 bit-flow 比特流 光纤、双绞线、中继器和集线器 & RJ-45(网线接口)
数据链路层 ARP、MAC、 FDDI、Ethernet、Arpanet、PPP、PDN frame 帧 网桥、二层交换机
网络层 IP、ICMP、ARP、RARP 数据包（packet） 路由器、三层交换机
传输层 TCP、UDP Segment/Datagram 四层交换机
会话层 SMTP、DNS 报文 QoS
表示层 Telnet、SNMP 报文 –
应用层 FTP、TFTP、Telnet、HTTP、DNS 报文 –
Three-way handshake
Four-way handshake
