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Learn what the Open Systems Interconnection (OSI) reference model is and how its seven layers of functions provide vendors and developers with a common language for discussing how messages should be transmitted between any two points in a telecommunication network. : Instead of serving as protocol, the OSI model has become a teaching tool that shows how different tasks within a network should be handled in order to promote error-free data transmission. An Introduction to the OSI ModelSource: Flickr/jonjohnson The open system interconnection model, better known as the OSI model, is a network map that was originally developed as a universal standard for creating networks. But instead of serving as a model with agreed-upon protocols that would be used worldwide, the OSI model has become a teaching tool that shows how different tasks within a network should be handled in order to promote error-free data transmission. These jobs are split into seven layers, each of which depends on the function’s “handed-off” from other layers. As a result, the OSI model also provides a guide for troubleshooting network problems by tracking them down to a specific layer. Here we’ll take a look at the layers of the OSI model and what functions they perform within a network.
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SUBJECT:COMPUTER
NETWORKSTOPIC:
OSI MODEL
CREATED BY:RUCHI MAURYATWINKAL PARMARSHIVALI SALUNKHE
OPEN SYSTEM INTERCONNECTION
OSI –open system interconnection model.
Conceptual model.Developed by ISO in 1984. ISO : Dedicated to defining global
communication and standards. logical framework
Introduction
7 Layers Of OSI Model
Application
Presentation
Session
Transport
Network
Data link
Physical
Top layer serve as window Interface between programme and
protocol stack.Enable to access network.
7. Application Layer
7. Application Layer
To Presentation Layer
From Presentation Layer
Network virtual terminalFile transfer , access and
managementMail services
7. Application LayerFunctions:
Also called Translation layer. concerned with syntax and semantics
of the information It can be viewed as the translator for
the network. translate data from a format into a
common format then translate the common format to
a format .Manages data-format information.
6. Presentation Layer
110011000111
H611001100011
1H6
From Application Layer To Application Layer
To Session Layer From Session Layer
6. Presentation Layer
6. Presentation LayerFunctions:
Character code TranslationData ConversionData CompressionData Encryption
hold ongoing communications (called a session) across a network.
orderly communication defines the format of the data establish and manages the
session reconnect the session if it
disconnects.
5. Session Layer
H5
syn syn syn
From Presentation Layer
To Transport Layer
Session Layer
From Transport Layer
To Presentation Layer
H5
syn syn syn
Session Layer
5. Session Layer
Session establishment, maintenance and termination.
Dialog Control security and access controlSynchronization
5. Session LayerFunctions:
End to end message deliveryError checking No duplication or errors are occurringMessage arrive in orderAcknowledgementRetransmits the data if error is found
4. Transport Layer
4. Transport Layer
Message acknowledgmentMessage traffic controlSession multiplexingFlow control
4. Transport LayerFunctions:
source to destination delivery.across multiple networks (links). converting logical addresses into
physical addresses.determines that how data transmits
between the network devices.Handles addressing messages for
delivery.
3. Network Layer
deciding how to route transmissions between computers
3. Network Layer
110011000111
H311001100011
1H3
From Transport Layer To Transport Layer
To Data Link Layer From Data Link Layer
Packet Packet
Logical-Physical Address Mapping Internetworking Logical AddressingRoutingPacketizingFragmentation
3. Network LayerFunctions:
provides a reliable linknode-to-node deliveryHandles special data frames
(packets)error-free transfer defines the format of data
2. Data Link Layer
Data Link layer consists of two sub-layers:1. Logical Link Control (LLC) sublayer2. Medium Access Control (MAC) sublayer
2. Data Link Layer
110011000111
H2 T211001100011
1H2 T2
From Network Layer To Network Layer
To Physical Layer From Physical Layer
Frame Frame
FramingPhysical AddressingFlow ControlError ControlAccess Control
2. Data Link LayerFunctions:
Lowest LayerTransmitting individual bitsMechanical electrical specification
1. Physical Layer
Transmission Media
110011000111
110011000111
H1 H1
Bit representationTransmission rateSynchronizingTransmission modePhysical Topology
1. Physical LayerFunctions:
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