1. ECE506/2 #1Spring 2009 © 2000-2009, Richard A. Stanley ECE537 Advanced and High Performance Networks 1: Network Layer Review Professor Richard A. Stanley, P.E.

2. ECE506/2 #2 Overview of Tonight’s Class Administration Is computer security a problem, or just an interesting topic? What is different between computer security and network security? Computer security objectives and approaches

3. ECE506/2 #3 Organizational Details Prof. Stanley contact information –Office: Atwater-Kent 303, but rarely there –Hours: by appointment, preferably after class –Phone: (508) 269-6482 –Email: rstanley@ece.wpi.edu

4. ECE506/2 #4 Administrivia Class will normally meet 4:00 – 8:00 PM every Wednesday here. Please be on time. We will hold 10 classes; cancellations will be announced in advance (except weather) Breaks as needed If class is cancelled for bad weather, you should receive notice. Double-check with ECE Dept. (5231) or with me if in doubt.

5. ECE506/2 #5 Recall We need to set up a way for notification of cancelled/late classes Please put the following information on the sheet going around: –Name –Email –Telephone Volunteer to be at the top of the list?

6. ECE506/2 #6 Course Text None. Additional material will be in the form of handouts and research reports

7. ECE506/2 #7 Course Web Page http://ece.wpi.edu//courses/ee579sw/ECE537 Slides will be posted to the page before class, barring any unfortunate problems

8. ECE506/2 #8 Policies Homework is due at the class following the one in which it is assigned. It will be accepted--with a one grade penalty--up to the second class after that in which it is assigned, but not after that, except in truly emergency situations. By definition, emergencies do not occur regularly. There is a difference between working in teams and submitting the same work. If work is a team product, it must be clearly labeled as such.

9. ECE506/2 #9 Elements of the Course Assignments: There will be weekly assignments, which will be graded Presentation: At the end of the course, student teams will present a report prepared on a cryptography-related subject. The presentation should be well-prepared and should give an overview of a special topic in cryptography (e.g. eCash, wireless security, SSL, biometric authentication systems etc.). Examinations: There will be a two written examinations that will cover all topics discussed in class. The questions will range from mild to hard.

10. ECE506/2 #10 Research Projects Teams of 3-5 individuals per project Research an advanced networking topic Prepare a report on the research Present findings –Note: a presentation is not the report copied into PowerPoint Given the nature of this course, we will do mini-reports throughout

11. ECE506/2 #11 Grading Grade components –Course exams (30%) –Homework (10%) –Class participation (10%) –Course projects (50%)

12. ECE506/2 #12 Course Topics Ad hoc networking Network extensions by wireless means Management challenges in high performance networks Colored and colorless networks Emerging network technologies Your preferences?

13. ECE506/4 #13 Link Layer: Ethernet Spring 2009 © 2000-2009, Richard A. Stanley

14. ECE506/4 #14 Internet Architecture

15. ECE506/4 #15 Fundamental Network Layer Function

16. ECE506/4 #16 Data Flow Across Layers

17. ECE506/4 #17 Protocol Layering and Data

18. ECE506/4 #18 Network Service Model

19. ECE506/4 #19 Virtual Circuits

20. ECE506/4 #20 Packet Switching

21. ECE506/4 #21 Packet Switching vs. Virtual Circuits

22. ECE506/4 #22 Routing Principles

23. ECE506/4 #23 1 2 3 0111 value in arriving packet’s header routing algorithm local forwarding table header value output link 0100 0101 0111 1001 32213221 Interplay between routing and forwarding

24. ECE506/4 #24 Datagram or VC network: why? Internet data exchange among computers –“elastic” service, no strict timing req. “smart” end systems (computers) –can adapt, perform control, error recovery –simple inside network, complexity at “edge” many link types –different characteristics –uniform service difficult ATM evolved from telephony human conversation: –strict timing, reliability requirements –need for guaranteed service “dumb” end systems –telephones –complexity inside network

25. ECE506/4 #25 Router Architecture Overview Two key router functions: run routing algorithms/protocol (RIP, OSPF, BGP) forwarding datagrams from incoming to outgoing link

26. ECE506/4 #26 Input Port Functions Decentralized switching: given datagram dest., lookup output port using forwarding table in input port memory goal: complete input port processing at ‘line speed’ queuing: if datagrams arrive faster than forwarding rate into switch fabric Physical layer: bit-level reception Data link layer: e.g., Ethernet see chapter 5

27. ECE506/4 #27 Three types of switching fabrics

28. ECE506/4 #28 Switching Via Memory First generation routers: traditional computers with switching under direct control of CPU packet copied to system’s memory speed limited by memory bandwidth (2 bus crossings per datagram) Input Port Output Port Memory System Bus

29. ECE506/4 #29 Switching Via a Bus datagram from input port memory to output port memory via a shared bus bus contention: switching speed limited by bus bandwidth 1 Gbps bus, Cisco 1900: sufficient speed for access and enterprise routers (not regional or backbone)

30. ECE506/4 #30 Switching Via An Interconnection Network Overcome bus bandwidth limitations Banyan networks, other interconnection nets initially developed to connect processors in multiprocessor Advanced design: fragmenting datagram into fixed length cells, switch cells through the fabric. Cisco 12000: switches Gbps through the interconnection network

31. ECE506/4 #31 Output Ports Buffering required when datagrams arrive from fabric faster than the transmission rate Scheduling discipline chooses among queued datagrams for transmission

32. ECE506/4 #32 Output port queueing buffering when arrival rate via switch exceeds output line speed queueing (delay) and loss due to output port buffer overflow!

33. ECE506/4 #33 Input Port Queuing Fabric slower than input ports combined -> queueing may occur at input queues Head-of-the-Line (HOL) blocking: queued datagram at front of queue prevents others in queue from moving forward queueing delay and loss due to input buffer overflow!

34. ECE506/4 #34 Routing Algorithms

35. ECE506/4 #35 A Link-State Routing Algorithm

36. ECE506/4 #36 Dijkstra’s Algorithm

37. ECE506/4 #37 Dijkstra’s Algorithm Example

38. ECE506/4 #38 Dijkstra’s Algorithm Discussion

39. ECE506/4 #39 Network Routing

40. ECE506/4 #40 Distance Vector Routing

41. ECE506/4 #41 Constructing Distance Vector

42. ECE506/4 #42 DV Algorithm Example

43. ECE506/4 #43 DV Algorithm Example

44. ECE506/4 #44 Maintaining the Distance Vector

45. ECE506/4 #45 Link Cost Changes

46. ECE506/4 #46 Link Cost Changes (con’t.)

47. ECE506/4 #47 DV Poisoned Reverse

48. ECE506/4 #48 Routing Loops

49. ECE506/4 #49 Distance Vector Example

50. ECE506/4 #50 Distance Vector to Routing Table

51. ECE506/4 #51 LS & DV Algorithms Compared

52. ECE506/4 #52 Internet Network Layer

53. ECE506/4 #53 IP Addressing

54. ECE506/4 #54 IP Network & Hierarchical Addressing

55. ECE506/4 #55 IP Addressing: Original Standard

56. ECE506/4 #56 IP Addressing: CIDR

57. ECE506/4 #57 DHCP

58. ECE506/4 #58 NAT

59. ECE506/4 #59 IP Packet Format (v4)

60. ECE506/4 #60 Packet Fragmentation & Reassembly

61. ECE506/4 #61 Routing on the Internet

62. ECE506/4 #62 Hierarchical Routing

63. ECE506/4 #63 Intra-/Inter-AS Routing

64. ECE506/4 #64 Intra-AS & Inter-AS Routing

65. ECE506/4 #65 Internet Routing

66. ECE506/4 #66 RIP: An Intra-AS Routing Protocol

67. ECE506/4 #67 RIP Example

68. ECE506/4 #68 RIP Example (2)

69. ECE506/4 #69 RIP Table Processing

70. ECE506/4 #70 RIP Table Example

71. ECE506/4 #71 OSPF: Another Intra-AS Routing Protocol

72. ECE506/4 #72 Hierarchical OSPF

73. ECE506/4 #73 Inter-AS Routing in the Internet

74. ECE506/4 #74 BGP Routing Protocol

75. ECE506/4 #75 BGP: Controlling Who Routes to You

76. ECE506/4 #76 BGP: Controlling Who Routes to You

77. ECE506/4 #77 BGP Routing Table: Whole Internet

78. ECE506/4 #78 Why Two-Level Intra- and Inter-AS Routing?

79. ECE506/4 #79 Summary Network layer takes care of routing datagrams Routing protocols either link status or autonomous system based IP a very common network layer protocol, but far from the only one! Routing protocols are complex and can be a topic of long study all by themselves

80. ECE506/4 #80Spring 2009 © 2000-2009, Richard A. Stanley Homework Research IPv6 and prepare a paper or presentation on this protocol (1100 words or so as a guideline). What does it bring that IPv4 does not provide? What does it lack? What is the good, the bad, and the ugly of this protocol?

81. ECE506/4 #81Spring 2009 © 2000-2009, Richard A. Stanley Disclaimer Parts of the lecture slides contain original work of James Kurose, Larry Peterson, Keith Ross, Eytan Modiano, Liudvikas Bukys, and Henry Warren, and remain copyrighted materials by the original owner(s). The slides are intended for the sole purpose of instruction of computer networks at Worcester Polytechnic Institute.