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The OSI - Open Systems Interconnection model

 Network Essentials  Understanding the OSI
OSI model
Layer Protocol data unit (PDU) Function[20]
Host
layers
7 Application Data High-level APIs, including resource sharing, remote file access
6 Presentation Translation of data between a networking service and an application; including character encodingdata compression and encryption/decryption
5 Session Managing communication sessions, i.e., continuous exchange of information in the form of multiple back-and-forth transmissions between two nodes
4 Transport SegmentDatagram Reliable transmission of data segments between points on a network, including segmentationacknowledgement and multiplexing
Media
layers
3 Network Packet Structuring and managing a multi-node network, including addressingrouting and traffic control
2 Data link Frame Reliable transmission of data frames between two nodes connected by a physical layer
1 Physical BitSymbol Transmission and reception of raw bit streams over a physical medium

 

 

The OSI - Open Systems Interconnection model