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CMPE 150 – Winter 2009

CMPE 150 – Winter 2009. Lecture 3 January 13, 2009 P.E. Mantey. CMPE 150 -- Introduction to Computer Networks. Instructor: Patrick Mantey mantey@soe.ucsc.edu http://www.soe.ucsc.edu/~mantey/ Office: Engr. 2 Room 595J Office hours: Tuesday 3-5 PM TA: Anselm Kia akia@soe.ucsc.edu

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CMPE 150 – Winter 2009

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  1. CMPE 150 – Winter 2009 Lecture 3 January 13, 2009 P.E. Mantey

  2. CMPE 150 -- Introduction to Computer Networks • Instructor: Patrick Mantey mantey@soe.ucsc.edu http://www.soe.ucsc.edu/~mantey/ • Office: Engr. 2 Room 595J • Office hours: Tuesday 3-5 PM • TA: Anselm Kia akia@soe.ucsc.edu • Web site: http://www.soe.ucsc.edu/classes/cmpe150/Winter09/ • Text: Tannenbaum: Computer Networks (4th edition – available in bookstore, etc. )

  3. Syllabus

  4. Today’s Agenda • Standards • Layered Network Architecture - review • Networks and History • Physical Layer • Signals and Systems • Fourier Analysis • Communication Theory

  5. Standards • Required to allow for interoperability between equipment • Advantages • Ensures a large market for equipment and software • Allows products from different vendors to communicate • Disadvantages • Freeze technology • May be multiple standards for the same thing

  6. Standards Organizations • IEEE • ANSI • Internet Society • ISO • ITU-T (formally CCITT) • ATM forum

  7. Network Standardization • Who’s Who in the Telecommunications World • Who’s Who in the International Standards World • Who’s Who in the Internet Standards World

  8. ITU • Main sectors • Radiocommunications • Telecommunications Standardization • Development • Classes of Members • National governments • Sector members • Associate members • Regulatory agencies

  9. IEEE 802 Standards The 802 working groups. The important ones are marked with *. The ones marked with  are hibernating. The one marked with † gave up.

  10. Metric Units The principal metric prefixes.

  11. Reference Models The TCP/IP reference model.

  12. Reference Models Protocols and networks in the TCP/IP model initially.

  13. Comparing OSI and TCP/IP Models • Concepts central to the OSI model • Services • Interfaces • Protocols

  14. A Critique of the OSI Model and Protocols • Why OSI did not take over the world • Bad timing • Bad technology • Bad implementations • Bad politics

  15. Bad Timing “The apocalypse of the two elephants.”

  16. A Critique of the TCP/IP Reference Model • Problems: • Service, interface, and protocol not distinguished • Not a general model • Host-to-network “layer” not really a layer • No mention of physical and data link layers • Minor protocols deeply entrenched, hard to replace

  17. Hybrid Model The hybrid reference model used by Tannenbaum

  18. Internet Layering Level 5 -- Application Layer (rlogin, ftp, SMTP, POP3, IMAP, HTTP..) Level 4 -- Transport Layer(a.k.a Host-to-Host) (TCP, UDP, ARP, ICMP, etc.) Level 3 -- Network Layer (a.k.a. Internet) (IP) Level 2 -- (Data)Link Layer / MAC sub-layer (a.k.a. Network Interface or Network Access Layer) Level 1 -- Physical Layer

  19. Example Networks • The Internet • Connection-Oriented Networks: X.25, Frame Relay, and ATM • Ethernet • Wireless LANs: 802:11

  20. Architecture of the Internet

  21. TCP/IP Reference Model Protocols and networks in the TCP/IP model initially.

  22. Characteristics • Internet Layer • Connectionless • Internet Protocol (IP) • Task is to deliver packets to destination • Transport Layer • Transmission Control Protocol (TCP) • Connection-oriented • Reliable • User Datagram Protocol (UDP) • Connectionless • Unreliable

  23. TELCO Networks • Connection-Oriented Networks • X.25 • Frame Relay • ATM • Fixed Route (set up at start of call) • Quality of Service • Billing – for connection time

  24. T’s and D’s http://www.netstreamsol.com.au/networking/notes/general/t1_e1_t3_e3_ds0_ds1_ds3.html

  25. T1 • Time-division multiplexed stream of 24 telephone channels • The basic technology upon which all T-carrier facilities are based • Uses a full-duplex digital signal over two wire pairs. • Bandwidth of 1.544 Mbps through telephone-switching network • Uses AMI or B8ZS coding.

  26. O’s

  27. SONET • Synchronous Optical NETwork • Synchronous Digital Hierarchy (SDH) Europe • Internet for CARRIERS • Worldwide standard • Multiplex multiple digital channels • Management support for • Operations • Administration • Maintenance

  28. X.25 and Frame Relay • X.25 -- First Public Data Network – 1970s • Call and connect “Data Terminal Equipment” • Simple packet structure • Implemented “virtual circuit” connections • Flow control, hop-by-hop error control • Multiplexing – up to 4095 circuits at a time • Frame Relay – 1980s (up to 2Mbps) • Limited error control, flow control • VC based packet switching --“wide area LAN”

  29. Asynchronous Transfer Mode • Vintage mid -1980s • Goal to unify voice networks and data networks • Packet Switching with virtual circuits (“channels”) • Fixed-length packets (“cells”) - @ 53 bytes • 5 byte header, 48 byte “payload” • Virtual channel header (VCI) • No retransmission link-by-link Error correction codes only • Envisioned to reach the end user • Used widely today for backbones

  30. ATM Virtual Circuits A virtual circuit.

  31. ATM Virtual Circuits (2) • An ATM cell.

  32. The ATM Reference Model • The ATM reference model.

  33. The ATM Reference Model (2) The ATM layers and sublayers and their functions

  34. Ethernet Architecture of the original Ethernet.

  35. Wireless LANs • (a) Wireless networking with a base station. • (b) Ad hoc networking.

  36. Wireless LANs (2) • The range of a single radio may not cover the entire system.

  37. Wireless LANs (3) A multicell 802.11 network.

  38. The ARPANET (a) Structure of the telephone system. (b) Baran’s proposed distributed switching system.

  39. The ARPANET (2) The original ARPANET design. IMP = Interface Message Processor (Honeywell DDP-316)

  40. The ARPANET (3) Growth of the ARPANET (a) December 1969. (b) July 1970.(c) March 1971. (d) April 1972. (e) September 1972.

  41. NSFNET The NSFNET backbone in 1988.

  42. http://www.internet2.edu/pubs/networkmap.pdf

  43. http://www.nlr.net/services/map/

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