02 Network Models(강의용)


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02 Network Models(강의용)

  1. 1. Ch.2 Network Models Lecturer: Tae-Hyong Kim (D132) [email_address]
  2. 2. Contents <ul><li>Introduction </li></ul><ul><li>Layered Tasks </li></ul><ul><li>Internet Model </li></ul><ul><li>OSI Model </li></ul><ul><li>Assignment #1 </li></ul>
  3. 3. Introduction <ul><li>The process of networking </li></ul><ul><ul><li>Think about the process of solving a mathematical problem </li></ul></ul><ul><ul><ul><li>Computer hardware </li></ul></ul></ul><ul><ul><ul><li>Operating system </li></ul></ul></ul><ul><ul><ul><li>Problem solving program </li></ul></ul></ul><ul><ul><ul><li> Layered architecture (shell, pyramid) </li></ul></ul></ul><ul><ul><li>How about sending an e-mail? </li></ul></ul>
  4. 4. Contents <ul><li>Introduction </li></ul><ul><li>Layered Tasks </li></ul><ul><li>Internet Model </li></ul><ul><li>OSI Model </li></ul><ul><li>Assignment #1 </li></ul>
  5. 5. Sender, Receiver, and Carrier <ul><li>Sending a letter </li></ul> There is a Hierarchy !
  6. 6. Contents <ul><li>Introduction </li></ul><ul><li>Layered Tasks </li></ul><ul><li>Internet Model </li></ul><ul><ul><li>Peer-to-peer Processes </li></ul></ul><ul><ul><li>Functions of Layers </li></ul></ul><ul><li>OSI Model </li></ul><ul><li>Assignment #1 </li></ul>
  7. 7. Internet Layers <ul><li>Today’s layered protocol stack </li></ul><ul><ul><li>5-layer model </li></ul></ul><ul><ul><li>TCP/IP protocol suite model </li></ul></ul>
  8. 8. Internet Layers <ul><li>Layers involved in sending message from device A to B </li></ul>
  9. 9. Peer-to-Peer Processes <ul><li>Layered architecture concept </li></ul>Physical interaction Logical interaction
  10. 10. Interfaces and Organization <ul><li>Organization of the Layers: three subgroups </li></ul><ul><ul><li>Network support layers: Layers 1, 2, and 3 </li></ul></ul><ul><ul><li>User support layer: layer 5 </li></ul></ul><ul><ul><li>Transport layer: layer 4 </li></ul></ul>
  11. 11. Overall View of the Layers
  12. 12. Functions of Layers <ul><li>Physical Layer </li></ul><ul><li>Data Link Layer </li></ul><ul><li>Network Layer </li></ul><ul><li>Transport Layer </li></ul><ul><li>Application Layer </li></ul>
  13. 13. Physical Layer <ul><li>For transmitting individual bits from one node to the next </li></ul><ul><li>Handles mechanical and electrical specification of the interface and transmission medium </li></ul>
  14. 14. Physical Layer <ul><li>Factors </li></ul><ul><ul><li>Physical characteristics of interfaces and media </li></ul></ul><ul><ul><li>Representation of bits </li></ul></ul><ul><ul><li>Data rate (transmission rate) </li></ul></ul><ul><ul><li>Synchronization of bits </li></ul></ul>
  15. 15. Data Link Layer <ul><li>For hop-to-hop (node-to-node) delivery of frames </li></ul><ul><li>makes the physical layer appear error free to the upper layer (network layer) </li></ul>
  16. 16. Data Link Layer <ul><li>Specific responsibilities </li></ul><ul><ul><li>Framing </li></ul></ul><ul><ul><li>Physical addressing </li></ul></ul><ul><ul><li>Flow control </li></ul></ul><ul><ul><li>Error control </li></ul></ul><ul><ul><li>Access control </li></ul></ul>
  17. 17. Data Link Layer <ul><li>hop-to-hop delivery </li></ul>
  18. 18. Data Link Layer <ul><li>Physical Addresses </li></ul>
  19. 19. Network Layer <ul><li>For Source-to-destination delivery of packets </li></ul>
  20. 20. Network Layer <ul><li>Specific responsibilities </li></ul><ul><ul><li>Logical addressing </li></ul></ul><ul><ul><li>Routing </li></ul></ul>
  21. 21. Network Layer <ul><li>Source-to-destination delivery </li></ul>
  22. 22. Network Layer <ul><li>Logical addresses (IP addresses) </li></ul>
  23. 23. Transport layer <ul><li>For process-to-process delivery of a message </li></ul>
  24. 24. Transport layer <ul><li>Specific responsibility </li></ul><ul><ul><li>Port addressing </li></ul></ul><ul><ul><li>Segmentation and reassembly </li></ul></ul><ul><ul><li>Connection control </li></ul></ul><ul><ul><li>Flow control </li></ul></ul><ul><ul><li>Error control </li></ul></ul>
  25. 25. Transport layer <ul><li>Process-to-process delivery </li></ul>
  26. 26. Transport layer <ul><li>Port addresses </li></ul>
  27. 27. Application Layer <ul><li>For providing services to the user </li></ul><ul><ul><li>E.g., user interfaces and user support </li></ul></ul>
  28. 28. Application Layer <ul><li>Specific services : Human interface services </li></ul><ul><ul><li>Mail Services </li></ul></ul><ul><ul><li>File transfer, access </li></ul></ul><ul><ul><li>Remote log-in </li></ul></ul><ul><ul><li>Accessing the World Wide Web </li></ul></ul>
  29. 29. Summary of Layers
  30. 30. Summary of Addresses ex. e-mail address, URL
  31. 31. Review Questions 2-1 <ul><li>Match the following to one of five Internet layers </li></ul><ul><ul><li>Route determination </li></ul></ul><ul><ul><li>Flow control </li></ul></ul><ul><ul><li>Interface to transmission media </li></ul></ul><ul><ul><li>Provides access to the end user </li></ul></ul>
  32. 32. Review Questions 2-2 <ul><li>In the following figure, computer A sends a message to computer D via LAN1, router R1, and LAN2. Show the contents of the packets and frames at the network and data link layer for each hop interface. </li></ul>
  33. 33. Review Questions 2-3 <ul><li>Suppose a computer sends a frame to another computer on a bus topology LAN. The physical destination address of the frame is corrupted during the transmission. What happens to the frame? How can the sender be informed about the situation? </li></ul><ul><ul><li>Consider error control feature of data link layer </li></ul></ul>
  34. 34. Contents <ul><li>Introduction </li></ul><ul><li>Layered Tasks </li></ul><ul><li>Internet Model </li></ul><ul><li>OSI Model </li></ul><ul><li>Assignment #1 </li></ul>
  35. 35. OSI Model <ul><li>Open System Interconnection model (in 1977) </li></ul><ul><ul><li>cf. ISO : a standard organization </li></ul></ul><ul><li>Standard : ISO 7498 (in 1984), ITU-T X.200 </li></ul><ul><li>7-layer model </li></ul>
  36. 36. Session Layer <ul><li>Controls the network dialog </li></ul><ul><ul><li>establishes, maintains, and synchronizes the interaction between communicating systems </li></ul></ul>
  37. 37. Session Layer <ul><li>Session </li></ul><ul><ul><li>The period of time for which two users remain logically connected </li></ul></ul><ul><ul><li>ex. Session layer dialog </li></ul></ul>
  38. 38. Session Layer <ul><li>Specific responsibility : User-oriented connection service </li></ul><ul><ul><li>Dialog control </li></ul></ul><ul><ul><li>Synchronization </li></ul></ul>
  39. 39. Presentation Layer <ul><li>concerned with the syntax and semantics of the information exchange between two systems </li></ul>
  40. 40. Presentation Layer <ul><li>Specific responsibility </li></ul><ul><ul><li>Code conversion </li></ul></ul><ul><ul><li>Encryption/Decryption </li></ul></ul><ul><ul><li>Compression </li></ul></ul>
  41. 41. The Internet and OSI Models
  42. 42. <ul><li>TCP/IP protocol suite was developed prior to the OSI model. </li></ul><ul><ul><li>Not match exactly with those in the OSI model </li></ul></ul><ul><ul><li>Around 1980, everyone was convinced that TCP/IP soon would be replaced by OSI protocols for layer 3-4. However, This did not happen </li></ul></ul><ul><li>Problem of the OSI model </li></ul><ul><ul><li>Repeated data exchanging between layers (much overhead) </li></ul></ul><ul><ul><li>Conceptual and Theoretical model </li></ul></ul>The Internet and OSI Models
  43. 43. <ul><li>Integrated Architecture </li></ul><ul><li>Layered Architecture </li></ul><ul><li>Cross-Layered Architecture </li></ul>Cross-Layered Architecture?
  44. 44. <ul><li>Exercises 17, 18, 19, 20, 23, 24, 25 </li></ul><ul><ul><li>Explain why for each answer </li></ul></ul><ul><li>Due Date </li></ul><ul><ul><li>The next class </li></ul></ul>Assignment #1