3.4 Seven layer OSI model Ver.1

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

Transmits raw bit stream over the physical medium

Decides which physical path the data will take

Ensures that data is in a usable format and is where data encryption occurs

Transmits data using transmission protocols including TCP and UDP

Human-computer interaction layer, where applications can access the network services

Defines the format of data on the network

Maintains connections and is responsible for controlling ports and sessions

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

Defines the format of data on the network

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Ensures that data is in a usable format and is where data encryption occurs

Transmits raw bit stream over the physical medium

Decides which physical path the data will take

Human-computer interaction layer, where applications can access the network services

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

Responsible for the actual physical connection between the devices and mainly defines the physical equipment standards, such as the interface type of the network cable, the interface type of the optical fibre and the transmission rate of various transmission media. Its main function is to transmit bit stream (that is, it is converted from 1, 0 to current strength for transmission, and after reaching the destination, it is converted to 1, 0, which is what we often call digital-to-analogue conversion and analogue-to-digital conversion). The data in this layer is called bits.

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

Responsible for the node to node delivery of the message and the main function of this layer is to make sure data transfer is error-free from one node to another. Defines how to format data for transmission and how to control access to physical media. This layer usually also provides error detection and correction to ensure reliable data transmission.

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

Provides connection and path selection between two host systems in networks located in different geographical locations. Also takes care of packet routing. The development of the Internet has greatly increased the number of users accessing information from various sites in the world and the network layer is the layer that manages this connection.

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

Defines some data transmission protocols and port numbers (WWW port 80, etc), such as: TCP (transmission control protocol, low transmission efficiency, strong reliability, used for high transmission reliability requirements, large data volume Data), UDP (User Datagram Protocol, which is the exact opposite of TCP characteristics, used to transmit data with low reliability requirements and small data volume, such as QQ chat data is transmitted in this way). It is mainly to segment and transmit the data received from the lower layer, and then reorganize it after reaching the destination address. Also provides the acknowledgement of the successful data transmission and re-transmits the data if an error is found. The data in this layer is referred to as segments.

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

Responsible for establishment of connection, maintenance of sessions, authentication and also ensures security. Through the transport layer (port number: transmission port and receiving port) to establish a data transmission path. Mainly initiate a session or accept session requests between your systems (devices need to know each other can be IP, MAC or host name).

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

To ensure that the information sent by the application layer of a system can be read by the application layer of another system. For example, a PC program communicates with another computer, one of which uses Extended Two Decimal Interchange Code (EBCDIC), and the other uses American Standard Code for Information Interchange (ASCII) to represent the same characters. If necessary, the presentation layer uses a common format to convert between multiple data formats.

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

It is the OSI layer closest to the user. This layer provides network services for user applications such as email, file transfer and terminal emulation.

Human-computer interaction layer, where applications can access the network services

Ensures that data is in a usable format and is where data encryption occurs

Maintains connections and is responsible for controlling ports and sessions

Transmits data using transmission protocols including TCP and UDP

Decides which physical path the data will take

Defines the format of data on the network

Transmits raw bit stream over the physical medium

APPLICATION LAYER

PRESENTATION LAYER

SESSION LAYER

TRANSPORT LAYER

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER