Brief introduction to tcp/ip protocol stack

Network layering

To the network layered , It is convenient to study computer network technology . The industry standard computer network layered design includes the following three . When we discuss network protocols , The reference is four layers Model .

OSI Seven layer model	TCP/IP Five layer model	TCP/IP Four layer model
application layer	application layer	application layer
The presentation layer
The session layer
Transport layer	Transport layer	Transport layer
The network layer	The network layer	The network layer
Data link layer	Data link layer	Network interface layer
The physical layer	The physical layer

The link layer 、 Data link layer and network interface layer are a concept .

The link layer

The link layer includes Device drivers and Network interface card , They jointly deal with the physical interface Hardware details .

Device drivers are software , Part of the operating system .
Network interface card is hardware , Also known as network card 、 network adapter , And network transmission media （ Twisted pair 、 Coaxial cable 、 Optical fiber, etc ） Connected to a .

The link layer = network card + Network card driver

Link layer protocols include ：ARP、RARP、 Ethernet protocol

The network layer

Network layer processing is different host Route and forward messages in the network .
Network layer protocols include ：IP、ICMP、IGMP

Transport layer

The transport layer is for different hosts Applications Provide data flow interaction .
The transport layer protocol has ：TCP、UDP

application layer

The application layer handles the details of a particular application .
Application layer protocols include ：Telnet、FTP、SMTP、SNMP

When processes communicate over the network , The application layer protocol handles the details of the application , Running on the operating system user Space ; Transport layer 、 The network layer and data link layer protocols handle the details of communication , Running on the operating system kernel Space .

Message encapsulation

When an application wants to pass TCP/IP When the protocol stack sends data , Data will be encapsulated layer by layer from top to bottom . Every floor will Add the relevant information of this layer to the head or tail of the sent data .

The receiver will strip each layer of information layer by layer , Until the data actually sent by the opposite end is obtained at the application layer .