The document discusses the seven-layer OSI model, which was developed by ISO in 1984 to provide networking standards. It defines each of the seven layers - physical, data link, network, transport, session, presentation and application - and their functions in transmitting data between two hosts. The physical layer transmits raw bits, while the upper layers encapsulate the data into frames, packets and segments with additional protocol data as it moves up the layers. [/SUMMARY]

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Learning OutcomesLearning OutcomesLearning OutcomesLearning Outcomes
1. Define seven layer of OSI Modelseven layer of OSI Modelseven layer of OSI Modelseven layer of OSI Model
2. Define functionsfunctionsfunctionsfunctions of each layer in OSI
Model
3. Use OSI Model to explain the
communication between two network
nodes
4. Describe data packets and framesdata packets and framesdata packets and framesdata packets and frames
5. Describe two types of addressingtwo types of addressingtwo types of addressingtwo types of addressing
covered by the OSI Model

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OSI Model?OSI Model?OSI Model?OSI Model?
The OSI (Open System Interconnection) model is
developed by ISO in 1984198419841984.
Why OSI?Why OSI?Why OSI?Why OSI? as a guidelines how network operatinghow network operatinghow network operatinghow network operating
systems communicatesystems communicatesystems communicatesystems communicate on a network.
OSI model was to provide a set of design standards
for equipment manufacturersfor equipment manufacturersfor equipment manufacturersfor equipment manufacturers.
ISO is the organization
OSI is the model
Note:Note:
7 Layer of OSI Model7 Layer of OSI Model7 Layer of OSI Model7 Layer of OSI Model
A good what to
remember the seven
layers is
All
People
Seem
To
Need
Data
Processing

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OSI Model vs Protocol
Data is transmitted from (Host A) to (Host B) the data flows down the 7
Layers at Host A and across the physical media in the form of binary
data, when it arrives at Host B the data travels back up through the
seven layers on Host B.

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An exchange using the OSI model
Host A Host B
Layer 7
Layer 6
Layer 5
Layer 4
Layer 3
Layer 2
Layer 1
Layer 7:Layer 7:Layer 7:Layer 7: ApplicationApplicationApplicationApplication
• DATADATADATADATA
• Used for applicationsapplicationsapplicationsapplications specifically written to run overspecifically written to run overspecifically written to run overspecifically written to run over
the networkthe networkthe networkthe network
• Provides services to end user’s applicationsend user’s applicationsend user’s applicationsend user’s applications
• Does not provide services to any other OSI layernot provide services to any other OSI layernot provide services to any other OSI layernot provide services to any other OSI layer
• ExampleExampleExampleExample: apps are file transfer, e-mail, NetBIOS-
based applications. Example: DNS; FTP; TFTP;
BOOTP; SNMP;RLOGIN; SMTP; MIME; NFS;
FINGER; TELNET; NCP; APPC; AFP; SMB

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Layer 6:Layer 6:Layer 6:Layer 6: PresentationPresentationPresentationPresentation
• DATADATADATADATA
• TranslatesTranslatesTranslatesTranslates from application to network format and
vice-versa (network format to application)
• EnsuresEnsuresEnsuresEnsures info from one system’s application layer canfrom one system’s application layer canfrom one system’s application layer canfrom one system’s application layer can
be read by another systembe read by another systembe read by another systembe read by another system
• Translates among multiple data formats
• Does encryption and decryption
Layer 5:Layer 5:Layer 5:Layer 5: SessionSessionSessionSession
• DATADATADATADATA
• Establishes, maintains and ends sessions across the
network.
• Responsible for name recognition (identification)name recognition (identification)name recognition (identification)name recognition (identification) so
only the designated parties can participate in the
session
• Examples:Examples:Examples:Examples: are interactive login and file transfer
connections, the session would connect and re-
connect if there was an interruption; recognize names
in sessions and register names in history

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Layer 4:Layer 4:Layer 4:Layer 4: TransportTransportTransportTransport
SEGMENTSSEGMENTSSEGMENTSSEGMENTS
Responsible for delivery of a messagedelivery of a messagedelivery of a messagedelivery of a message from one
process to another
Two transport protocols: Transmission ControlTransmission ControlTransmission ControlTransmission Control
Protocol (TCP) and User Datagram Protocol (UDP)Protocol (TCP) and User Datagram Protocol (UDP)Protocol (TCP) and User Datagram Protocol (UDP)Protocol (TCP) and User Datagram Protocol (UDP)
A train is a good analogy => the data is divided intodivided intodivided intodivided into
identical unitsidentical unitsidentical unitsidentical units
• Example protocols: TCP, ARP, RARP, SPXNWLink,
NetBIOS / NetBEUI, ATP
Layer 3:Layer 3:Layer 3:Layer 3: NetworkNetworkNetworkNetwork
PACKETSPACKETSPACKETSPACKETS
• Determine the path for data from the source to the
destination computer. It manage switchingswitchingswitchingswitching and routingroutingroutingrouting
of data packets based on network addresses concern
on PACKET ROUTING.
• Protocols: IP (Internet Protocol), IPX (Internet
Protocol Exchange)
DataDataDataData H3H3H3H3
IP Address

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Layer 3:Layer 3:Layer 3:Layer 3: NetworkNetworkNetworkNetwork (cont…)(cont…)(cont…)(cont…)
Layer 2:Layer 2:Layer 2:Layer 2: Data LinkData LinkData LinkData Link
FRAMESFRAMESFRAMESFRAMES
This layer is where the network packets arenetwork packets arenetwork packets arenetwork packets are
translatedtranslatedtranslatedtranslated into raw bitsraw bitsraw bitsraw bits (example: 00110101) to be
transmitted on the physical layer.
Responsible for transmitting frames from one node to
the next. This is also a layer that uses the most basic
addressing scheme, MAC AddressesMAC AddressesMAC AddressesMAC Addresses

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Physical Address (Mac Address) ???Physical Address (Mac Address) ???Physical Address (Mac Address) ???Physical Address (Mac Address) ???
MAC (Media Access Control) address is the unique hardware
address that is installed to the network card by its manufacturer
Layer 1:Layer 1:Layer 1:Layer 1: PhysicalPhysicalPhysicalPhysical
BITSBITSBITSBITS
Physical layer defines the cable or physical medium.
Responsible for transmitting individual bits from one
node to the next.

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To be Continue….
I don’t stopstopstopstop when I’m tiredI’m tiredI’m tiredI’m tired.
I only stopstopstopstop when I’m doneI’m doneI’m doneI’m done…