Chapter02 -- networking standards and the osi model


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Basic Networking Guide

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Chapter02 -- networking standards and the osi model

  1. 1. Chapter 2: Networking Standards and the OSI Model Network+ Guide to Networks
  2. 2. Objectives <ul><li>Identify organizations that set standards for networking </li></ul><ul><li>Describe the purpose of the OSI Model and each of its layers </li></ul><ul><li>Explain specific functions belonging to each OSI Model layer </li></ul>
  3. 3. Objectives (continued) <ul><li>Understand how two network nodes communicate through the OSI Model </li></ul><ul><li>Discuss the structure and purpose of data packets and frames </li></ul><ul><li>Describe the two types of addressing covered by the OSI Model </li></ul>
  4. 4. Networking Standards Organizations <ul><li>Standards are documented agreements containing technical specifications </li></ul><ul><ul><li>ANSI (American National Standards Institute) is an organization composed of more than a thousand representatives from industry and government who together determine standards for the electronics industry and other fields, such as chemical and nuclear engineering, health and safety, and construction </li></ul></ul>
  5. 5. Networking Standards Organizations (continued) <ul><ul><li>ANSI also represents the United States in setting international standards </li></ul></ul><ul><ul><li>EIA (Electronic Industries Alliance) is a trade organization composed of representatives from electronics manufacturing firms across the United States </li></ul></ul>
  6. 6. Networking Standards Organizations (continued) <ul><ul><li>TIA (Telecommunications Industry Association) Focuses on standards for information technology, wireless, satellite, fiber optics, and telephone equipment </li></ul></ul><ul><ul><ul><li>TIA/EIA alliance are its guidelines for how network cable should be installed in commercial buildings, known as the “TIA/EIA 568-B Series.” </li></ul></ul></ul>
  7. 7. <ul><ul><li>IEEE (Institute of Electrical and Electronics Engineers), or “I-triple-E,” is an international society composed of engineering professionals </li></ul></ul><ul><ul><ul><li>IEEE goals are to promote development and education in the electrical engineering and computer science fields </li></ul></ul></ul>Networking Standards Organizations (continued)
  8. 8. <ul><ul><li>ISO (International Organization for Standardization), headquartered in Geneva, Switzerland, is a collection of standards and organizations representing 148 countries </li></ul></ul><ul><ul><ul><li>ISO ’s goal is to establish international technological standards to facilitate global exchange of information and barrier-free trade </li></ul></ul></ul>Networking Standards Organizations (continued)
  9. 9. <ul><ul><li>The ITU (International Telecommunication Union) is a specialized United Nations agency that regulates international telecommunications, including radio and TV frequencies, satellite and telephony specifications, networking infrastructure, and tariffs applied to global communications </li></ul></ul>Networking Standards Organizations (continued)
  10. 10. Networking Standards Organizations (continued) <ul><ul><li>ISOC (Internet Society), founded in 1992, is a professional membership society that helps to establish technical standards for the Internet </li></ul></ul><ul><ul><ul><li>ISOC oversees groups with specific missions, such as the IAB and IETF </li></ul></ul></ul>
  11. 11. Networking Standards Organizations (continued) <ul><ul><li>IAB (Internet Architecture Board) is a technical advisory group of researchers and technical professionals interested in overseeing the Internet’s design and management </li></ul></ul><ul><ul><li>IETF (Internet Engineering Task Force), the organization that sets standards for how systems communicate over the Internet—in particular, how protocols operate and interact </li></ul></ul>
  12. 12. Networking Standards Organizations (continued) <ul><ul><li>IANA and ICANN </li></ul></ul><ul><ul><ul><li>Every computer / host on a network must have a unique address </li></ul></ul></ul><ul><ul><ul><li>Internet Assigned Numbers Authority (IANA) kept records of available and reserved IP addresses and determined how addresses were issued out </li></ul></ul></ul><ul><ul><ul><li>Internet Corporation for Assigned Names and Numbers (ICANN), a private, nonprofit corporation and is now ultimately responsible for IP addressing and domain name management </li></ul></ul></ul>
  13. 13. The OSI Model <ul><li>In the early 1980s, ISO began work on a universal set of specifications that would enable computer platforms across the world to communicate openly </li></ul><ul><li>This model, called the Open Systems Interconnection (OSI) Model, divides network communications into seven layers: </li></ul>
  14. 14. The OSI Model (continued)
  15. 15. The OSI Model (continued) <ul><li>Application Layer </li></ul><ul><ul><li>Separates data into protocol data units (PDUs) </li></ul></ul><ul><ul><ul><li>Application layer PDUs progress down through OSI Model layers 6, 5, 4, 3, 2, and 1 </li></ul></ul></ul><ul><ul><ul><li>Data traverses the network until it reaches the second computer’s Physical layer </li></ul></ul></ul><ul><ul><ul><li>Transfer of information happens in milliseconds </li></ul></ul></ul>
  16. 16. The OSI Model (continued)
  17. 17. The OSI Model (continued) <ul><li>Application Layer </li></ul><ul><ul><li>Does not include software applications, such as Microsoft Word or Netscape </li></ul></ul><ul><ul><li>Services communicate between software programs and lower-layer network services </li></ul></ul><ul><ul><li>File, print, message, database, and application services </li></ul></ul>
  18. 18. The OSI Model (continued) <ul><li>Application Layer </li></ul><ul><ul><li>World Wide Web (WWW) </li></ul></ul><ul><ul><li>Email - SMTP (Simple Mail Transport Protocol or the X.400) </li></ul></ul>
  19. 19. The OSI Model (continued)
  20. 20. The OSI Model (continued)
  21. 21. The OSI Model (continued) <ul><li>Presentation Layer </li></ul><ul><ul><li>Protocols at the Presentation layer accept Application layer data and format it </li></ul></ul><ul><ul><li>Serves as a translator and are the standards which are involved in multimedia </li></ul></ul><ul><ul><li>Presentation layer protocols perform the coding, compression and also manage data encryption and decryption </li></ul></ul>
  22. 22. The OSI Model (continued) <ul><li>Session Layer </li></ul><ul><ul><li>Protocols in the Session layer coordinate and maintain communications between two nodes </li></ul></ul><ul><ul><li>Session refers to a connection for ongoing data exchange between two parties </li></ul></ul>
  23. 23. The OSI Model (continued) <ul><li>Session Layer (continued) </li></ul><ul><ul><li>Session layer’s functions are establishing and keeping alive the communications link for the duration of the session </li></ul></ul><ul><ul><ul><li>Keep the communication secure </li></ul></ul></ul><ul><ul><ul><li>Synchronizing the dialog between the two nodes </li></ul></ul></ul><ul><ul><ul><li>Determining whether communications have been cut off, and, if so, figuring out where to restart transmission and terminating communications </li></ul></ul></ul>
  24. 24. The OSI Model (continued) <ul><li>Transport Layer </li></ul><ul><ul><li>Protocols in the Transport layer accept data from the Session layer and manage end to-end delivery </li></ul></ul><ul><ul><li>Ensures that the data is transferred from point A to point B reliably, in the correct sequence, and without errors </li></ul></ul>
  25. 25. The OSI Model (continued) <ul><li>Transport Layer (continued) </li></ul><ul><ul><li>Without Transport layer services, data could not be verified or interpreted by its recipient </li></ul></ul><ul><ul><li>Handles flow control </li></ul></ul><ul><ul><li>Some Transport layer protocols take steps to ensure that data arrives exactly as it was sent. </li></ul></ul>
  26. 26. The OSI Model (continued) <ul><li>Transport Layer (continued) </li></ul><ul><ul><li>Such protocols are known as connection-oriented, </li></ul></ul><ul><ul><li>TCP is one example of a connection-oriented protocol </li></ul></ul><ul><ul><ul><li>Three Step Process </li></ul></ul></ul><ul><ul><ul><ul><li>Request (Client sends) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Acknowledgment (ACK) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Client Acknowledgement (ACK) </li></ul></ul></ul></ul>
  27. 27. The OSI Model (continued) <ul><li>Transport Layer (continued) </li></ul><ul><ul><li>Checksum: method of error checking </li></ul></ul><ul><ul><li>Connectionless protocols </li></ul></ul><ul><ul><li>Process is known as segmentation </li></ul></ul><ul><ul><ul><li>Necessary for data units to match a network’s maximum transmission unit (MTU) </li></ul></ul></ul>
  28. 28. The OSI Model (continued) <ul><li>Transport Layer (continued) </li></ul><ul><ul><li>Reassembly </li></ul></ul><ul><ul><li>Sequencing </li></ul></ul><ul><ul><ul><li>Identifying segments that belong to the same group </li></ul></ul></ul>
  29. 29. The OSI Model (continued)
  30. 30. The OSI Model (continued)
  31. 31. The OSI Model (continued) <ul><li>Network Layer </li></ul><ul><ul><li>Primary function of protocols at the Network layer </li></ul></ul><ul><ul><ul><li>Translate network addresses </li></ul></ul></ul><ul><ul><ul><li>Decide how to route data </li></ul></ul></ul><ul><ul><li>Network layer addresses </li></ul></ul><ul><ul><ul><li>Also called logical addresses or virtual addresses </li></ul></ul></ul>
  32. 32. The OSI Model (continued) <ul><li>Network Layer (continued) </li></ul><ul><ul><li>Routers belong in the Network layer </li></ul></ul><ul><ul><li>Perform Fragmentation </li></ul></ul>
  33. 33. The OSI Model (continued)
  34. 34. The OSI Model (continued) <ul><li>Data Link Layer </li></ul><ul><ul><li>Primary function of protocols is to divide data into distinct frames that can then be transmitted by the Physical layer </li></ul></ul><ul><ul><li>IEEE has divided the Data Link layer into two sublayers </li></ul></ul><ul><ul><ul><li>Logical Link Control (LLC) </li></ul></ul></ul><ul><ul><ul><li>Media Access Control (MAC) </li></ul></ul></ul>
  35. 35. The OSI Model (continued)
  36. 36. The OSI Model (continued) <ul><li>Physical Layer </li></ul><ul><ul><li>Lowest, or first, layer of the OSI Model </li></ul></ul><ul><ul><li>Protocols at the Physical layer </li></ul></ul><ul><ul><ul><li>Accept frames from the Data Link layer </li></ul></ul></ul><ul><ul><ul><li>Generate voltage so as to transmit signals </li></ul></ul></ul><ul><ul><ul><li>Receiving data detect voltage and accept signals </li></ul></ul></ul><ul><ul><ul><li>Pass on to the Data Link layer </li></ul></ul></ul>
  37. 37. Applying The OSI Model
  38. 38. Applying The OSI Model (continued) <ul><li>Communication Between Two Systems </li></ul><ul><ul><li>At each layer of the OSI Model, some information is added to the original data </li></ul></ul>
  39. 39. Applying The OSI Model (continued)
  40. 40. Applying The OSI Model (continued) <ul><li>Frame Specifications </li></ul><ul><ul><li>Two major categories of frame types </li></ul></ul><ul><ul><ul><li>Ethernet </li></ul></ul></ul><ul><ul><ul><ul><li>developed at Xerox in the early 1970s </li></ul></ul></ul></ul><ul><ul><ul><li>Token Ring </li></ul></ul></ul><ul><ul><ul><ul><li>developed by IBM in the 1980s </li></ul></ul></ul></ul>
  41. 41. IEEE Networking Specifications <ul><li>“ Project 802” </li></ul><ul><ul><li>Effort to standardize physical and logical elements of a network </li></ul></ul><ul><ul><ul><li>Frame types and addressing </li></ul></ul></ul><ul><ul><ul><li>Connectivity, </li></ul></ul></ul><ul><ul><ul><li>Networking media, </li></ul></ul></ul><ul><ul><ul><li>Error checking algorithms, </li></ul></ul></ul><ul><ul><ul><li>Encryption, </li></ul></ul></ul>
  42. 42. IEEE Networking Specifications (continued) <ul><li>“ Project 802” (continued) </li></ul><ul><ul><ul><li>Emerging technologies, </li></ul></ul></ul><ul><ul><ul><li>And more </li></ul></ul></ul><ul><ul><li>Can be applied to the layers of the OSI Model </li></ul></ul>
  43. 43. IEEE Networking Specifications (continued)
  44. 44. Chapter Summary <ul><li>Standards are documented agreements containing precise criteria </li></ul><ul><li>Significant standards organizations </li></ul><ul><ul><li>ANSI, EIA/TIA, IEEE, ISO, ITU, ISOC, IANA, and ICANN </li></ul></ul>
  45. 45. Chapter Summary (continued) <ul><li>Excellent model for understanding communications </li></ul><ul><li>Protocols in the Application layer, the seventh layer of the OSI Model, enable software programs to negotiate </li></ul>
  46. 46. Chapter Summary (continued) <ul><li>Protocols in the Presentation layer, the sixth OSI Model layer, serve as translators between the application and the network </li></ul>
  47. 47. Chapter Summary (continued) <ul><li>Protocols in the Session layer, the fifth OSI Model layer, </li></ul><ul><ul><li>coordinate and maintain links between two devices </li></ul></ul><ul><ul><li>synchronize dialog </li></ul></ul><ul><li>Primary function of protocols in the Transport layer, the fourth OSI Model layer, is to oversee end-to-end data delivery </li></ul>
  48. 48. Chapter Summary (continued) <ul><li>Protocols in the Network layer, the third OSI Model layer, manage logical addressing and determine routes </li></ul>
  49. 49. Chapter Summary (continued) <ul><li>Network layer addresses, also called logical or virtual addresses, are assigned to devices through operating system software </li></ul><ul><li>Primary function of protocols at the Data Link layer, the second layer of the OSI Model, is to organize data they receive from the Network layer into frames </li></ul>
  50. 50. Chapter Summary (continued) <ul><li>Data Link layer is subdivided into the Logical Link Control and MAC sublayers </li></ul><ul><ul><li>LLC sublayer ensures a common interface </li></ul></ul><ul><ul><li>MAC sublayer is responsible for adding physical address data to frames </li></ul></ul><ul><li>Protocols at the Physical layer generate and detect voltage </li></ul>
  51. 51. Chapter Summary (continued) <ul><li>Protocols at the Physical layer generate and detect voltage </li></ul>
  52. 52. Chapter Summary (continued) <ul><li>Data request from a software program is received by the Application layer protocols and is transferred down through the layers of the OSI Model until it reaches the Physical layer </li></ul><ul><li>Data frames are small blocks of data with control, addressing, and handling information attached to them </li></ul>
  53. 53. Chapter Summary (continued) <ul><li>Data request from a software program is received by the Application layer protocols and is transferred down through the layers of the OSI Model until it reaches the Physical layer </li></ul><ul><li>Data frames are small blocks of data with control, addressing, and handling information attached to them </li></ul>
  54. 54. Chapter Summary (continued) <ul><li>In addition to frame types and addressing schemes, the IEEE Networking Specifications apply to connectivity, networking media, error checking algorithms, encryption, emerging technologies, and more </li></ul><ul><li>Significant 802 standards are: 802.3, which describes Ethernet; 802.5, which describes Token Ring; and 802.11, which describes wireless networking </li></ul>