4. Examlpe of OSI Layer, thier definition in order

• 7. APPLICATION LAYER- is a term used in categorizing protocols and methods in archetictural models of computer networking. Both the OSI model and the Internet Protocol Suite (TCPI/IP) contain an application layer.
• 6. PRESENTATION LAYER- is responsible for the delivery and formatting of information to the apllication layer for the further processing or display.
• 5. SESSION LAYER- provides the mechanism for opening, closing and managing a session between end-user application procesess, i.e. a semi-permanent dailague.
• 4. TRANSPORT LAYER- is a group of methods and protocols within a layered architecture of network components within which it is responsible for encapsulating application data blocks into data units (datagrams, segments) suitable for transferto the network infrastructure for transmission to the destination host, or managing the reverse transaction by abstracting network data grams and delivering thier payload to an application.
• 3. NETWORK LAYER- provides the funtionaland procedural means of transferring variable lenght data sequences from a source to a destination host via one or more networks while maintaining the quality of service and error control functions.
• 2. DATA LINK LAYER- is concerned with local delivery of frames between devices of the same LAN
• 1. PHYSICAL LAYER- consits of the basic hardware transmission technologies of a network . It is a fundamental layer underlying the logical data structures of the higer level functions of a network.