Answer:

OSI model is a way of describing how different applications and protocols interact on network-aware devices.

Functions of each Layer:

Physical Layer(Layer 1):This layer defines the physical and electrical characteristics of the network. Helps to pass strings(data) of ones and zeros down the wire.

Device:Hub, NIC, Repeater.. etc

Data Link Layer:

It defines the acess strategy for sharing the physical medium. Helps convert the bits into frame.

Devices: Bridge, Switch

Network Layer:

Layer 3 is the Network Layer, providing a means for communicating open systems to establish, maintain and terminate network connections.

Device:Router

Transport Layer:

The main function of Session Layer is to ensure data reliability and integrity.

Session Layer:

It provides two communicating presentation entities to exchange data with eachother.

Presentation Layer:

Application data is either unpacked or packed only in this layer. Protocol conversions, encryption/decryption and graphics expansion all takes place here.

Application Layer:

This is where you find your end-user and end-application protocols, such as telnet, ftp, and mail(pop3 and smtp).

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