OSI (Open Systems Interconnection) is reference model for how applications can
communicate over a network and a reference model is a conceptual framework for
understanding relationships.
OSI layers:
The seven Open Systems Interconnection layers are:
Application
Provides
access to the OSI environment for users and also provides distributed
information services.
Presentation
Provides
independence to the application processes from differences in data
representation (syntax).
Session
Provides
the control structure for communication between applications; establishes,
manages, and terminates connections (sessions) between cooperating
applications.
Transport
Provides
reliable, transparent transfer of data between end points; provides end-to-end
error recovery and flow control.
Network
Network
Provides upper layers with independence from the data transmission and
switching technologies used to connect systems; responsible for establishing,
maintaining, and terminating connections.
Data
Link
Provides
for the reliable transfer of information across the physical link; sends blocks
(frames) with the necessary synchronization, error control, and flow control.
Physical
Physical Concerned with transmission of
unstructured bit stream over physical medium; deals with the mechanical,
electrical, functional, and procedural characteristics to access the physical
medium.
Book Reference:
Wireless Communication and Networks by William Stallings (2nd Edition)
