The International Standard Organization has a well-defined model for Communication
Systems known as Open System Interconnection, or the OSI Model. This layered model
is a conceptualized view of how one system should communicate with the other, using
various protocols defined in each layer. Further, each layer is designated to a welldefined
part of communication system. For example, the Physical layer defines all the
components of physical nature, i.e. wires, frequencies, pulse codes, voltage transmission
etc. of a communication system.
The OSI Model has the following seven layers:
Application Layer (Layer-7): This is where the user application sits that needs
to transfer data between or among hosts. For example: HTTP, file transfer
application (FTP) and electronic mail etc.
Presentation Layer (Layer-6): This layer helps to understand data
representation in one form on a host to other host in their native representation.
Data from the sender is converted to on-the-wire data (general standard format)
and at the receiver’s end it is converted to the native representation of the
receiver.
Session Layer (Layer-5): This layer provides session management capabilities
between hosts. For example, if some host needs a password verification for
access and if credentials are provided then for that session password verification
does not happen again. This layer can assist in synchronization, dialog control
and critical operation management (e.g., an online bank transaction).
Transport Layer (Layer-4): This layer provides end-to-end data delivery
among hosts. This layer takes data from the above layer and breaks it into
smaller units called Segments and then gives it to the Network layer for
transmission.
Network Layer (Layer-3): This layer helps to uniquely identify hosts beyond
the subnets and defines the path which the packets will follow or be routed to
reach the destination.
Data Link Layer (Layer-2): This layer takes the raw transmission data (signal,
pulses, etc.) from the Physical Layer and makes Data Frames, and sends that to
the upper layer and vice versa. This layer also checks any transmission errors
and sorts it out accordingly.
Physical Layer (Layer-1): This layer deals with hardware technology and actual
communication mechanism such as signaling, voltage, cable type and length, etc.
Systems known as Open System Interconnection, or the OSI Model. This layered model
is a conceptualized view of how one system should communicate with the other, using
various protocols defined in each layer. Further, each layer is designated to a welldefined
part of communication system. For example, the Physical layer defines all the
components of physical nature, i.e. wires, frequencies, pulse codes, voltage transmission
etc. of a communication system.
The OSI Model has the following seven layers:
Application Layer (Layer-7): This is where the user application sits that needs
to transfer data between or among hosts. For example: HTTP, file transfer
application (FTP) and electronic mail etc.
Presentation Layer (Layer-6): This layer helps to understand data
representation in one form on a host to other host in their native representation.
Data from the sender is converted to on-the-wire data (general standard format)
and at the receiver’s end it is converted to the native representation of the
receiver.
Session Layer (Layer-5): This layer provides session management capabilities
between hosts. For example, if some host needs a password verification for
access and if credentials are provided then for that session password verification
does not happen again. This layer can assist in synchronization, dialog control
and critical operation management (e.g., an online bank transaction).
Transport Layer (Layer-4): This layer provides end-to-end data delivery
among hosts. This layer takes data from the above layer and breaks it into
smaller units called Segments and then gives it to the Network layer for
transmission.
Network Layer (Layer-3): This layer helps to uniquely identify hosts beyond
the subnets and defines the path which the packets will follow or be routed to
reach the destination.
Data Link Layer (Layer-2): This layer takes the raw transmission data (signal,
pulses, etc.) from the Physical Layer and makes Data Frames, and sends that to
the upper layer and vice versa. This layer also checks any transmission errors
and sorts it out accordingly.
Physical Layer (Layer-1): This layer deals with hardware technology and actual
communication mechanism such as signaling, voltage, cable type and length, etc.
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