OSI ISO MODEL

It is a model.

It is not a protocol.

ISO(International Standards Organisation)
OSI(Open System Interconnect)

OSI is a model developed by ISO which describes how data from application on one computer can be transferred to an application on another computer.

I know u need to know short-cut....right?????

All   People  Seem  To  Need  Data  Processing.

(Application,Presentation,Session,Transport,Network,DataLink,
Physical Layers.)

The Seven Layers of the OSI Model
Layer	Name	Description
1	Physical	Governs the layout of cables and devices such as repeaters and hubs.
2	Data Link	Provides MAC addresses to uniquely identify network nodes and a means for data to be sent over the Physical layer in the form of packets. Bridges and switches are layer 2 devices.
3	Network	Handles routing of data across network segments.
4	Transport	Provides for reliable delivery of packets.
5	Session	Establishes sessions between network applications.
6	Presentation	Converts data so that systems that use different data formats can exchange information.
7	Application	Allows applications to request network services.

Layer	Description	Examples
7. Application	Responsible for initiating or services the request.	SMTP, DNS, HTTP, and Telnet
6. Presentation	Formats the information so that it is understood by the receiving system.	Compression and encryption depending on the implementation
5. Session	Responsible for establishing, managing, and terminating the session.	NetBIOS
4. Transport	Breaks information into segments and is responsible for connection and connectionless communication.	TCP and UDP
3. Network	Responsible for logical addressing and routing	IP, ICMP, ARP, RIP, IGRP, and routers
2. Data Link	Responsible for physical addressing, error correction, and preparing the information for the media	MAC address, CSMA/CD, switches, and bridges
1. Physical	Deals with the electrical signal.	Cables, connectors, hubs, and repeaters