Shulou(Shulou.com)06/01 Report--

The following is a seven-layer model of OSI drawn using Emacs's artist-mode. You can remember it in one sentence. I don't remember where I saw it. It's probably "All People Seem To Need Data Process".

# + BEGIN_SRC ditaa: file p_w_picpaths/network01.png +-+ | cRED Application | +-+ | cPNK Presentation | +- -+ | cYEL Session | +-+ | cBLU Transport | +-+ | cGRE Network | +- -- + | c1AC DataLink | +-+ | c1AB Physical | +-+ # + END_SRC

The details of each layer are as follows:

Layer 7: the application layer defines the interface for communication and data transmission in the network-user programs

Provide standard services, such as transfer and processing of virtual terminals, files, and tasks

Layer 6: the presentation layer masks the differences in data formats between different systems

Specify the data transfer format for stand-alone structures

Encoding and decoding of data; encryption and decryption; compression and decompression

Layer 5: session layer manages user sessions and conversations

Control the establishment and hang-up of logical connections between users

Report an error that occurred at the upper level

Layer 4: the transport layer manages end-to-end information transmission in the network

Provide reliable and orderly packet delivery through error correction and flow control mechanisms

Provides delivery of connectionless packets

Layer 3: the network layer defines how data is transmitted between network devices

Route packets based on a unique network device address

Provide flow and congestion control to prevent the loss of network resources

Layer 2: the data link layer defines the program that operates the communication connection

Encapsulate a packet into a data frame

Monitor and correct packet transmission errors

Layer 1: the physical layer defines the physical way to send data through network devices

As an interface between network media and devices

Define optical, electrical, and mechanical properties.

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