Classification of osi seven-layer model

1: osI / * Open Systems Interconnection reference Model * /

I. 1 is divided into seven floors:

7. Application layer: object oriented to users, realizing all kinds of applications

6. Presentation layer: representation of data, security, compression,

5. Session layer: establish, manage, and abort a session

4. Transport layer: defines the protocol and port number for transmitting data, as well as data flow control and error checking

3. Network layer: forward according to the logical address to make the route choose the best path for different networks

two。 Data link layer: addressing and error checking according to the physical address of the hardware

1. Physical layer: establish, maintain, disconnect physical links

(define physical and electrical signals)

1.1 protocols and data units corresponding to the seven layers:

Application layer: http, telnet, ftp, tftp, smtp, pop3 and other apdu

Presentation layer: ppdu

Session layer spdu

Transport layer tcp / udp tpdu

Network layer icmp igmp arp packet / Datagram

Block-by-block data frame of the data link layer

A string of bit streams in the physical layer

Data unit

Iso (International Standards Organization): an OSI model of open systems interconnection is proposed.