Chapter
ISO-OSI Reference Model and
IEEE Standards

© N. Ganesan, Ph.D. , All
rights reserved.
Chapter Objectives
• Discuss the most popular ISO-OSI 7layer communication reference model
• Explain the reference model a...
Module 1

An Overview of ISO and its
7-Layer OSI Model

© N. Ganesan, Ph.D. , All
rights reserved.
Models and Standards in
Communication
• Communication
– Established standards
– Standards are known as protocols

• Implem...
ISO and OSI Defined
• ISO
– International Standards Organization

• OSI
– Open Systems Interconnect
OSI Model Background
• Introduced in 1978 and revised in 1984
• Formulates the communication process
into structured layer...
The Layered Approach to
Communication
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Ph...
Division of Layers
7. Application
6. Presentation
5. Session
4. Transport

Upper Layers
Middle Layer

3. Network
2. Data L...
The Function of a Layer
• Each layer deals with one aspect of
networking
– Layer 1 deals with the communication media

• E...
Role of Layers
Node A
7. Application
6. Presentation

Data In
To/from
Node B

1. Physical
Data Out
Communication Between Layers
7. Application
Data
Encapsulation
6. Presentation
Data
Stripping
5. Session
The Role of Layers in Point-topoint Communication
Node a
7. Application

1. Physical

Node b
7. Application

1.Physical
Virtual Communication Between
Layers
7. Application

7. Application

3. Network

3. Network
End of Module 1
Module 2

The ISO Upper Layers

© N. Ganesan, Ph.D. , All
rights reserved.
Module Objectives
• Application Layer
• Presentation Layer
• Session Layer
• Transport Layer
• Network Layer
7. Application Layer
• Purpose
– User application to network service
interface

• Examples
– File request from server
– E-...
Application Layer Function
• General network access
• Flow control
• Error recovery
6. Presentation Layer
• Purpose
– Formats data for exchange between points
of communication
• Ex: Between nodes in a netwo...
Presentation Layer Function
• Protocol conversion
• Data translation
• Encryption
• Character set conversion
• Expansion o...
Redirector Example
F:/PUR/ORDER

C:/CORRES/USDA

REDIRECTOR
TO SERVER

TO LOCAL
DISK
5. Session Layer
• Purpose
– Oversee a communication session
• Establish
• Maintain
• Terminate

• Example
Session Layer Function
• Performs name recognition and related
security
• Synchronization between sender and
receiver
• As...
4. Transport Layer
• Purpose
– Repackage proper and efficient delivery of
packages
• Error free
• In sequence
• Without du...
Transport Layer Function
• For sending data
– Repackage the message to fit into packets
• Split long messages
• Assemble s...
3. Network Layer
• Purpose
– Addressing and routing the packets

• Example application at the router
– If the packet size ...
Network Layer Function
• Address messages
• Address translation from logical to
physical
– Ex: nganesa ----------> 102.13....
End of Module 2
Module 3
The ISO Lower Layers

© N. Ganesan, Ph.D. , All
rights reserved.
2. Data Link Layer
• Purpose
– Manages the flow of data over the physical
media

• Responsible for error-free transmission...
Data Link Layer Function
• Point of origin
– Packages data for transmission over physical line

• Receiving end
– Packages...
Data Link Layer Subdivision
• Improvement to ISO Model
• Logical Link Control (LLC) sub-layer
– Manages service access poi...
Logical Link Control
Media Access Control
Application
• Network Interface Card driver
NETWORK
SOFTWARE

NETWORK
CARD

NIC Driver
facilitates da...
1. Physical Layer
• Purpose
– Deals with the transmission of 0s and 1s
over the physical media
• Translation of bits into ...
Physical Layer Function
• Encode bits into signals
– Carry data from the h higher layers

• Define the interface to the ca...
Lower Layers Application Areas
• Special significance to network card design
• Applies to general LAN hardware design
– Ex...
End of Module 3
Module 4
Summary of ISO-OSI Functional
Layers

© N. Ganesan, Ph.D. , All
rights reserved.
Layer Operations
• At each layer, additional information is
added to the data packet
• An example would be information
rel...
Formatting of Data Through the
Layers
Application Header

Presentation Header

Network Header

Data Link Header and Traile...
Packet : General Format
Header

Trailer

Data

A general concept of packets serves as a prerequisite to
the understanding ...
Some Header Information Added at
Various Layers
• Packet arrival information
• Receiver’s address
• Sender’s address
• Syn...
Data
• Actual data
• May contain error correction code
– Performed on individual characters of the data
– Example: Parity
...
Some Trailer Information Added at
Various Layers
• Error correction code
– Character oriented
– VRC (Parity Checking)

• P...
A Note on CRC
• Used widely
• Sophisticated
– Polynomial of deferent degrees are used
for error correction
– Example: Degr...
Some of the Major Components of
the Data Packet
Receiver’s
Address

Control
Data
Data

Error
Correction
Protocol

Start/sy...
Standardizing Packet Formatting
• Packets must conform to a standard in order
for the nodes in a network to be able to
com...
End of Module 4
Module 5

The IEEE 802 Group and the
Standards

© N. Ganesan, Ph.D. , All
rights reserved.
IEEE Background
• Institution of Electrical and Electronic
Engineers (IEEE)
– A professional non-profit organization

• Pr...
IEEE 802 Focus
• OSI Reference
– Data Link layer
– Physical layer

• Areas
– Network cards and cables
– Network electronic...
Upper Layer Focus
• IETF
• W3C
• ISO/IEC
• The above agencies focus on setting
standards on higher level protocol
– TCP, I...
IEEE 802 Committees And
Responsibilities
• 802.1
– Internetworking

• 802.2
– Logical Link Control (LLC)

• 802.3
– CSMA/C...
IEEE 802 Committees and
Responsibilities (Cont.)
• 802.5
– Token Ring LAN

• 802.6
– Metropolitan Area Network

• 802.7
– ...
IEEE 802 (Cont.)
• 802.9
– Integrated Voice/Data Networks

• 802.10
– Network Security

• 802.11
– Wireless Networks

• 80...
OSI Sub-Layer Reference to
IEEE 802 Standards
Logical
Link
Control
(LLC)

Media
Access
Control
(MAC)

802.2
802.1 for
both...
End of Module 5
END OF MODULE
END OF CHAPTER
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Iso layer detail

  1. 1. Chapter ISO-OSI Reference Model and IEEE Standards © N. Ganesan, Ph.D. , All rights reserved.
  2. 2. Chapter Objectives • Discuss the most popular ISO-OSI 7layer communication reference model • Explain the reference model and standards relevant to network communications • Describe the different IEEE standards that apply to different types of networks
  3. 3. Module 1 An Overview of ISO and its 7-Layer OSI Model © N. Ganesan, Ph.D. , All rights reserved.
  4. 4. Models and Standards in Communication • Communication – Established standards – Standards are known as protocols • Implementation – A framework is helpful in the design of hardware and software for communication – ISO-OSI Model serves this purpose – ISO-OSI supersedes the TCP/IP model
  5. 5. ISO and OSI Defined • ISO – International Standards Organization • OSI – Open Systems Interconnect
  6. 6. OSI Model Background • Introduced in 1978 and revised in 1984 • Formulates the communication process into structured layers • There are seven layers in the model, hence the name the 7-Layer model • The model acts as a frame of reference in the design of communications and networking products
  7. 7. The Layered Approach to Communication 7. Application 6. Presentation 5. Session 4. Transport 3. Network 2. Data Link 1. Physical
  8. 8. Division of Layers 7. Application 6. Presentation 5. Session 4. Transport Upper Layers Middle Layer 3. Network 2. Data Link 1. Physical Lower Layers
  9. 9. The Function of a Layer • Each layer deals with one aspect of networking – Layer 1 deals with the communication media • Each layer communicates with the adjacent layers – In both directions – Ex: Network layer communicates with: • Transport layer • Data Link layer • Each layer formats the data packet – Ex: Adds or deletes addresses
  10. 10. Role of Layers Node A 7. Application 6. Presentation Data In To/from Node B 1. Physical Data Out
  11. 11. Communication Between Layers 7. Application Data Encapsulation 6. Presentation Data Stripping 5. Session
  12. 12. The Role of Layers in Point-topoint Communication Node a 7. Application 1. Physical Node b 7. Application 1.Physical
  13. 13. Virtual Communication Between Layers 7. Application 7. Application 3. Network 3. Network
  14. 14. End of Module 1
  15. 15. Module 2 The ISO Upper Layers © N. Ganesan, Ph.D. , All rights reserved.
  16. 16. Module Objectives • Application Layer • Presentation Layer • Session Layer • Transport Layer • Network Layer
  17. 17. 7. Application Layer • Purpose – User application to network service interface • Examples – File request from server – E-mail services – etc.
  18. 18. Application Layer Function • General network access • Flow control • Error recovery
  19. 19. 6. Presentation Layer • Purpose – Formats data for exchange between points of communication • Ex: Between nodes in a network • Example: – Redirector software • Formats for transmission to the server
  20. 20. Presentation Layer Function • Protocol conversion • Data translation • Encryption • Character set conversion • Expansion of graphics command
  21. 21. Redirector Example F:/PUR/ORDER C:/CORRES/USDA REDIRECTOR TO SERVER TO LOCAL DISK
  22. 22. 5. Session Layer • Purpose – Oversee a communication session • Establish • Maintain • Terminate • Example
  23. 23. Session Layer Function • Performs name recognition and related security • Synchronization between sender and receiver • Assignment of time for transmission – Start time – End time etc.
  24. 24. 4. Transport Layer • Purpose – Repackage proper and efficient delivery of packages • Error free • In sequence • Without duplication • Example
  25. 25. Transport Layer Function • For sending data – Repackage the message to fit into packets • Split long messages • Assemble small messages • On receiving data – Perform the reverse – Send an acknowledgment to the sender • Solve packet problems – During transmission and reception
  26. 26. 3. Network Layer • Purpose – Addressing and routing the packets • Example application at the router – If the packet size is large, splits into small packets
  27. 27. Network Layer Function • Address messages • Address translation from logical to physical – Ex: nganesa ----------> 102.13.345.25 • Routing of data – Based on priority – Best path at the time of transmission • Congestion control
  28. 28. End of Module 2
  29. 29. Module 3 The ISO Lower Layers © N. Ganesan, Ph.D. , All rights reserved.
  30. 30. 2. Data Link Layer • Purpose – Manages the flow of data over the physical media • Responsible for error-free transmission over the physical media • Assures error-free data submission to the Network Layer
  31. 31. Data Link Layer Function • Point of origin – Packages data for transmission over physical line • Receiving end – Packages data for submission to the network layer • Deals with network transmission protocols – IEEE 802. protocols
  32. 32. Data Link Layer Subdivision • Improvement to ISO Model • Logical Link Control (LLC) sub-layer – Manages service access points (logical link) – Error and flow control • Media Access Control (MAC) sub-layer – Applies directly to network card communication – Access control
  33. 33. Logical Link Control
  34. 34. Media Access Control Application • Network Interface Card driver NETWORK SOFTWARE NETWORK CARD NIC Driver facilitates data transfer
  35. 35. 1. Physical Layer • Purpose – Deals with the transmission of 0s and 1s over the physical media • Translation of bits into signals • Example – Pulse duration determination – Transmission synchronization – etc.
  36. 36. Physical Layer Function • Encode bits into signals – Carry data from the h higher layers • Define the interface to the card – – – – Electrical Mechanical Functional Example: Pin count on the connector
  37. 37. Lower Layers Application Areas • Special significance to network card design • Applies to general LAN hardware design – Exceptions • Routers etc. • 802. standards – Centered around the lower layers – Applies to networks
  38. 38. End of Module 3
  39. 39. Module 4 Summary of ISO-OSI Functional Layers © N. Ganesan, Ph.D. , All rights reserved.
  40. 40. Layer Operations • At each layer, additional information is added to the data packet • An example would be information related to the IP protocol that is added at Layer 3
  41. 41. Formatting of Data Through the Layers Application Header Presentation Header Network Header Data Link Header and Trailer Session Header Transport Header Physical Frame Preamble
  42. 42. Packet : General Format Header Trailer Data A general concept of packets serves as a prerequisite to the understanding of the ISO-OSI model.
  43. 43. Some Header Information Added at Various Layers • Packet arrival information • Receiver’s address • Sender’s address • Synchronization character
  44. 44. Data • Actual data • May contain error correction code – Performed on individual characters of the data – Example: Parity • Size may vary – Depending on the protocol – Example • 802.3 specifies range of data packet length
  45. 45. Some Trailer Information Added at Various Layers • Error correction code – Character oriented – VRC (Parity Checking) • Packet oriented error correction codes – LRC – CRC
  46. 46. A Note on CRC • Used widely • Sophisticated – Polynomial of deferent degrees are used for error correction – Example: Degrees 16, 32 etc. • CRC-32 is a more stringent error checking procedure than CRC-16
  47. 47. Some of the Major Components of the Data Packet Receiver’s Address Control Data Data Error Correction Protocol Start/synch Information Sender’s Address
  48. 48. Standardizing Packet Formatting • Packets must conform to a standard in order for the nodes in a network to be able to communicate with one another • The International Standards Organization (ISO) has provided a reference model • Standards are established for operations at each layer of the ISO/OSI model in the form of protocols
  49. 49. End of Module 4
  50. 50. Module 5 The IEEE 802 Group and the Standards © N. Ganesan, Ph.D. , All rights reserved.
  51. 51. IEEE Background • Institution of Electrical and Electronic Engineers (IEEE) – A professional non-profit organization • Project group 802 – Responsible for setting standards relating to the physical link of the network
  52. 52. IEEE 802 Focus • OSI Reference – Data Link layer – Physical layer • Areas – Network cards and cables – Network electronic/optical/ wireless communication standard as they apply to the lower two layers mentioned above – WAN connectivity
  53. 53. Upper Layer Focus • IETF • W3C • ISO/IEC • The above agencies focus on setting standards on higher level protocol – TCP, IP etc.
  54. 54. IEEE 802 Committees And Responsibilities • 802.1 – Internetworking • 802.2 – Logical Link Control (LLC) • 802.3 – CSMA/CD • 802.4 – Token Bus LAN
  55. 55. IEEE 802 Committees and Responsibilities (Cont.) • 802.5 – Token Ring LAN • 802.6 – Metropolitan Area Network • 802.7 – Broadband Technical Advisory Group • 802.8 – Fiber-Optic Technical Advisory Group
  56. 56. IEEE 802 (Cont.) • 802.9 – Integrated Voice/Data Networks • 802.10 – Network Security • 802.11 – Wireless Networks • 802.12 – Demand Priority Access LANs – Ex: 100BaseVG-AnyLAN
  57. 57. OSI Sub-Layer Reference to IEEE 802 Standards Logical Link Control (LLC) Media Access Control (MAC) 802.2 802.1 for both. 802.3 802.4 802.5 802.12
  58. 58. End of Module 5
  59. 59. END OF MODULE END OF CHAPTER

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