Open Systems Interconnection Model (OSI)

Open Systems Interconnection Model : -

The OSI model is the basic model describing the data movement through a network. The Open Systems Interconnection (OSI) reference model describes how information from a software application in one computer moves through a network medium to a software application in another computer. The OSI reference model is a conceptual model composed of seven layers, each specifying particular network functions. The OSI model divides the tasks involved with moving information between networked computers into seven smaller, more manageable task groups. A task or group of tasks is then assigned to each of the seven OSI layers.

The following list details the seven layers of the Open System Interconnection (OSI) reference model:

• Layer 7—Application layer (A)
• Layer 6—Presentation layer (P)
• Layer 5—Session layer (S)
• Layer 4—Transport layer (T)
• Layer 3—Network layer (N)
• Layer 2—Data Link layer (D)
• Layer 1—Physical layer (P)

Tip To Remember

People Do Need To Send Packets Away.
The first letter of each word is related to the alphabet associated with the name of the OSI layer. P of People stands for Physical Layer of the OSI model and so on.

Protocol

The OSI model provides a conceptual framework for communication between computers, but the model itself is not a method of communication. Actual communication is made possible by using communication protocols. In the context of data networking, a protocol is a formal set of rules and conventions that governs how computers exchange information over a network medium. A protocol implements the functions of one or more of the OSI layers. A wide variety of communication protocols exist, but all tend to fall into one of the following groups: LAN protocols, WAN protocols, network protocols, and routing protocols. LAN protocols operate at the network and data link layers of the OSI model and define communication over the various LAN media. WAN protocols operate at the lowest three layers of the OSI model and define communication over the various wide-area media. Routing protocols are network-layer protocols that are responsible for path determination and traffic switching. Finally, network protocols are the various upper-layer protocols that exist in a given protocol suite.

This being the beginning session, I haven’t dwelled into the details. Lets start small and end big! So till then get these fundamentals ingrained in your mind.