OSI Model:

OSI Model:

Open System Interconnection is a reference model to describe how data communication takes place between one computer to other computer in a network.

it was proposed by International Organization for Standardization (ISO)

•  OSI is evolved from experiences with ARPANET

Format                       Layer                                             Brief Function

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Data                 -- Application Layer               -- DHCP, FTP, HTTP

Data                 -- Presentation Layer            -- File type ex: JPEG, TXT; Compression

Data                 -- Session Layer                   -- Security, connection establishment,                                                                                           connection release, type of communication

Segment            -- Transport Layer              -- Error control, messages to segments,                                                                                       TCP/UDP

Packet              -- Network Layer                 -- Logical Address & Translation logical to                                                                                    Physical address

Frame              -- Data link Layer                 -- Raw data to logical structure called Frame, A  
                                                                        frame includes where the data to go, FCS                                                                                 (Frame Check Sequence)

Bits                   -- Physical Layer                 -- for controlling the function interface, such as                                                                            transmission techniques, type of connection

Note: OSI model was developed in Feb 1980, so this is called as 802.xx standard

            Where 80 -- 19"80", 2 -- Feb.