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Chapter. Packet and Circuit Switching. Chapter Objectives. Explain the concept of packet switching Give sample application areas of packet switching Describe circuit switching Compare and contrast packet switching with circuit switching. Chapter Modules. Packet switching

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  1. Chapter Packet and Circuit Switching

  2. Chapter Objectives • Explain the concept of packet switching • Give sample application areas of packet switching • Describe circuit switching • Compare and contrast packet switching with circuit switching

  3. Chapter Modules • Packet switching • Packet switching applications • Circuit switching applications

  4. Module Packet Switching

  5. Packet Switching Preview • Explain the concept of a path or a route taken by a packet • Study the difference between static and dynamic paths? • Relate appropriately the terms packet switching and circuit switching to the terms dynamic and static paths • Explore the path taken by a packets in dynamic routing when a packet travels from its origin to its destination

  6. The Concept of Path in Communication • A path is a route for data to travel between two nodes in a network • Dynamic path • In this case, the path often changes from packet to packet • Example: Packet Switching • Static path • Path is initially established and it remains unchanged for the duration of the communication session • Example: Circuit Switching

  7. Packet Switching Network Packet 2 New York Los Angeles Packet 1 Miami

  8. Salient Points of Packet Switching • Path • Each packet may take a different path to its destination • Best path is heuristically determined at each node • Packet switching • Path may be switched among packets • Hence, the term packet switching

  9. Key Words • Packet and circuit switching • Dynamic and static paths

  10. End of Module

  11. Module Advantages and Disadvantages of Packet Switching

  12. Questions • What are the major advantages and disadvantages of packet switching? • Could the Internet be called a packet switching network? • How does packet switching help in supporting multiple communication sessions? • How does a web server support multiple access to its contents? Explain in terms of packets that travel from the web server to their various destinations.

  13. Questions (continued) • What are the implications of packet switching to the transmission of audio and video in real time? • How are the above problems addressed in streaming?

  14. Major Advantages • Better utilization of the network segments in terms of the usage of the network paths • Ability to engage in multiple communication sessions

  15. Dynamic Assignment of Paths New York Las Vegas Los Angeles Miami

  16. Support for Multiple Communication Sessions Session 1 Session 2 New York Las Vegas Los Angeles Miami

  17. Disadvantage or a Concern • Packets may not arrive at their destination in the order in which they were originally transmitted • The above possibility exists because of the different paths that are taken by the different packets

  18. Order of Arrival of Packets Packet 2 New York Packet 1 Los Angeles Miami Packet 2 may arrive earlier than Packet 1.

  19. Packet Assembly • Packets are assembled to preserve the order of transmission • Packets arriving earlier are held in a buffer • The order of arrival is critical and in certain cases the order is time sensitive as well

  20. Transmission of Audio and Video in Packet Switching • Transmission of audio and video are time sensitive • Timely arrival of packet is important • The process that would ensure the orderly and timely arrival of data packets is known as streaming • Streaming also compresses the data to minimize bandwidth requirements thus ensuring that the packets have adequate bandwidth to travel to the destination in the order in which they are supposed to arrive at the destination

  21. Buffering in Streaming • Streamed audio or video is often buffered to ensure that the audio or video is played continuously

  22. Advantages And Disadvantages • Advantages • Efficient use of the network paths • Engage in multiple sessions • Disadvantages • Additional hardware and software resources are required to assemble and route the packets • If real-time continuity is stipulated then the data must be subjected to a process known as streaming

  23. Special Concerns • Audio and video transmission • Streaming is used • Voice Over IP (VoIP) is designed deploy telephony over the Internet

  24. Newer Advancements for Real Time Transmission of Information • Faster Internet speed • Better technology • IPv6 • Better streaming technologies

  25. Questions • What are the major advantages and disadvantages of packet switching? • Could the Internet be called as a packet switching network? • How does packet switching help in supporting multiple communication sessions? • How does a web server support multiple access to its contents? Explain in terms of packets that travel from the web server to their various destinations on the Internet.

  26. Questions (continued) • What are the implications of packet switching to the transmission of audio and video in real time? • Relate the above to Voice over IP transmission. • How are the above problems addressed in streaming?

  27. End of Module

  28. MODULE Packet Switching Applications

  29. Questions • Give a simple example of packet switching application • Relate packet switching to multiple session applications on the Internet and give examples of multiple session applications • Describe audio transmission challenges on packet-switched networks

  30. Questions (Continued) • List the packet switching technologies used in WANs • Explain the emergence of the concept of fixed length packets or cells in packet switching networks • Name a cell based transmission technology and state its applications

  31. Internet: An Application of Packet Switching Packet N1 Internet Server New York Ramp Packet M1 Los Angeles Miami Server in Los Angeles supports multiple access to the web over a packet switched connection.

  32. Support for Multiple Sessions Session LA Session HU Packet 2 New York Los Angeles Packet 1 Miami Houston Packets are displayed on different sessions on the screen.

  33. Applications Using Multiple-Sessions • Sharing • Collaboration • Multiple access to an Internet server • etc.

  34. Packet Delivery SCREEN Packets from Origin 2: M1, M2 Packets from origin 1: N1, N2 Sharing of Word document on Internet under Microsoft NetMeeting

  35. Audio Transmission Over Packet Switching Network • Relatively high speeds are required on the network • Data compression and other techniques are used to ensure continuity know as streaming • Sample applications: • Audio streaming on the Internet • RealAudio is an example of a streaming software

  36. Usage of Packet Switching • Large computer networks with multiple routers • WAN in general • Internet in particular

  37. Packet Switching WAN Technologies • Past and Present • X.25 Packet Switching • Present and Near Future • Frame Relay • Present and Future • Asynchronous Transfer Mode (ATM) • ATM is also known as Cell Relay

  38. ATM • Asynchronous Transmission Method (ATM) • Based on fixed length packets • Switches instead of routers are used to route the information on a network • This is the emerging technology in WAN transmission • (Include more information on ATM)

  39. Recollecting the Concept of Cell Data Packet varies in size Data Cell is of fixed length

  40. Questions • Give a simple example of packet switching application • Relate packet switching to multiple session applications on the Internet and give examples of multiple session applications • Describe audio transmission challenges on packet-switched networks

  41. Questions (Continued) • List the packet switching technologies used in WANs • Explain the emergence of the concept of fixed length packets or cells in packet switching networks • Name a cell based transmission technology and state its applications

  42. End of Module

  43. MODULE 5 Circuit Switching

  44. Questions • Explain the concepts of circuit switching. How does it function? • What are the advantages and disadvantages of circuit switching? • Name some applications of circuit switching • Compare circuit switching with packet switching

  45. Circuit Switching Network Established Circuit Switch New York Los Angeles Circuit established and maintained for entire duration of communication.

  46. Defining Characteristics of Circuit Switching • Establish (switch) a path (circuit) between two nodes of communication • Maintain the circuit for the full duration of communication session

  47. Advantages of Circuit Switching • Continuity assured in the order of transmission • Audio can be transmitted without streaming provided adequate bandwidth is available • Otherwise streaming is necessary • The overhead is low in switching a circuit

  48. Disadvantages of Circuit Switching • Inefficient use of the paths that are available within a network • This may lead to circuit saturation • Users can be locked out of the network • Multiple sessions cannot easily be implemented although it is possible to have multiple sessions

  49. Circuit Saturation Established Circuit New York Los Angeles Miami Saturation point.

  50. Areas of Applications • Voice/Video communications • Telephone network • Both analog and digital telecommunication lines can be circuit switched • ISDN

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