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The OSI
model:-
The Open Systems
Interconnection Reference Model (OSI Reference Model or OSI Model) is an
abstract description for layered communications and computer network
protocol design. It was developed as part of the Open Systems
Interconnection (OSI) initiative.[1] In its most basic form, it divides
network architecture into seven layers which, from top to bottom, are the
Application, Presentation, Session, Transport, Network, Data-Link, and
Physical Layers. It is therefore often referred to as the OSI Seven Layer
Model.
A layer is a
collection of conceptually similar functions that provide services to the
layer above it and receives service from the layer below it. For example,
a layer that provides error-free communications across a network provides
the path needed by applications above it, while it calls the next lower
layer to send and receive packets that make up the contents of the path.
7 Application Layer -
File Transfer, Email, Remote Login
6 Presentation Layer
- ASCII Text, Sound (syntax layer)
5 Session Layer -
Establish/manage connection
4 Transport Layer -
End-to-end control & error checking (ensure complete transfer): TCP
3 Network Layer -
Routing and Forwarding Address: IP
2 Data Link Layer -
Two party communication: Ethernet
1 Physical Layer -
How to transmit signal; coding Hardware means of sending and
receiving data on a carrier
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