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Computer Network Architecture ECE 156 Fall 2007

Computer Network Architecture ECE 156 Fall 2007. Romit Roy Choudhury Dept. of ECE and CS. Course Logistics. Welcome to ECE 156. Timings: Tu/Thu 1:15pm to 2:30pm Location: 212 Engineering Course TA: TBA Insructor: Romit Roy Choudhury New faculty in ECE & CS.

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Computer Network Architecture ECE 156 Fall 2007

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  1. Computer Network ArchitectureECE 156 Fall 2007 Romit Roy Choudhury Dept. of ECE and CS

  2. Course Logistics

  3. Welcome to ECE 156 • Timings: Tu/Thu 1:15pm to 2:30pm • Location: 212 Engineering • Course TA: TBA • Insructor: Romit Roy Choudhury New faculty in ECE & CS. Ph.D from UIUC in Summer, 2006 Research in Networking and Distributed Sys. • Office hours: Tu/Th 2:30-3:30 or appointment Email me at romit@ee.duke.edu and visit me at 203 Hudson Hall

  4. Welcome to ECE 156 • Prerequisite: ECE 52 Else, come and talk to me • Further courses: • ECE 256 (previously 299.02): Wireless Networking and Mobile Computing • Spring 2008

  5. Welcome to ECE 156 • Class broadcast email: ece_156_01@ee.duke.edu • Course Website: http://www.ee.duke.edu/~romit/courses/f07/ece156-f07-networking.html • Most course related information will be posted on the website • Please check the course website frequently

  6. Welcome to ECE 156 • Make up classes • Will be occasionaly necessary due to travel • Would like to schedule on a case by case basis

  7. Welcome to ECE 156 • Grading: • Participation/Presentation: 10% • Homework: 20% • Programming Assignments: 20% • 1 mid-term exam: 20% • Final exam: 30% • Programming project may be in groups of 2 • One of the exams is likely to be open book

  8. Finally • Academic honesty • Please please please … • A few points is not worth a tarnished career • In the long run, GPA does not matter as much as you think it does • More importantly • Let’s not make the CNN headlines for the wrong reasons anymore

  9. Course Summary(Very Briefly)

  10. Course information • Course materials: • Text: Computer Networking: A Top Down Approach Featuring the Internet, J. Kurose & K. Ross, Addison Wesley, 3rd ed., 2005 • Class notes • Some supplementary reading material

  11. Introductory (first) course in computer networking Undergrads, early MS students learn principles of computer networking learn practice of computer networking Internet architecture/protocols as case study Real wireless networks as case studies Intro to next generation networking What is this course about?

  12. By the time you are finished … You understand variety of concepts (not just factoids) Internet, HTTP, DNS, P2P, … Sockets, Ports, … Congestion Control, Flow Control, TCP, … Routing, Basic Graphs, Djikstra’s Algorithm, IP, … DSL Vs Cable, Aloha, CSMA, TDMA, Token, 802.11, … Security, RSA, … Cellular Networks, Mobile Networks, Satellite Networks, … Wireless Multihop Networks (ad hoc, mesh, WLANs) Sensor Networks … Course information If you understand 75% of these terms, you shouldn’t be here

  13. What this Course Does Not Cover • Not a “communications” course • Does not cover • Modulation schemes • Transmitter/Receiver design • Signal processing and antenna design • Etc. • This is course on • Understading, analysing, and (perhaps) designing of protocols and algorithms in wired/wireless networking systems

  14. What’s the difference between Communications And Networking Systems

  15. Finally • I cannot / will not / should not be speaking alone in class • Questions • Comments • Disagreements • Debates … are highly encouraged • This course can be real fun • Whether it will be … • Is up to you and me

  16. Hello! I am ECE 156

  17. Acknowledgments: Many slides borrowed from Jim Kurose (UMass)

  18. On the Shoulders of Giants • 1961: Leonard Kleinrock published a work on packet switching • 1962: J. Licklider described a worldwide network of computers called Galactic Network • 1965: Larry Roberts designed the ARPANET that communicated over long distance links • 1971: Ray Tomilson invents email at BBN • 1972: Bob Kahn and Vint Cerf invented TCP for reliable packet transport

  19. On the Shoulders of Giants … • 1973: David Clark, Bob Metcalfe implemented TCP and designed ethernet at Xerox PARC • 1975: Paul Mockapetris developed DNS system for host lookup • 1980: Radia Perlman invented spanning tree algorithm for bridging separate networks • Things snowballed from there on …

  20. What we have today is beyond any of the inventors’ imagination …

  21. And YOU are here

  22. And by “YOU” I mean …

  23. “Cool” internet appliances Web-enabled toaster + weather forecaster IP picture frame http://www.ceiva.com/ World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html Internet phones

  24. And Of Course YOU and ME …

  25. InterNetwork • Millions of end points (you, me, and toasters) are connected over an network • Many end points can be addressed by numbers • Many others lie behind a virtual end point • Many networks form a bigger network • The overall strcture called the Internet • With a capital I • Defined as the network of networks

  26. roughly hierarchical at center: “tier-1” ISPs (e.g., MCI, Sprint, AT&T, Cable and Wireless), national/international coverage treat each other as equals Tier-1 providers interconnect (peer) privately Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP

  27. Seattle POP: point-of-presence DS3 (45 Mbps) OC3 (155 Mbps) OC12 (622 Mbps) OC48 (2.4 Gbps) Tacoma to/from backbone peering New York … …. Stockton Cheyenne Chicago Pennsauken Relay Wash. DC San Jose Roachdale Kansas City … … … Anaheim to/from customers Atlanta Fort Worth Orlando Tier-1 ISP: e.g., Sprint Sprint US backbone network

  28. “Tier-2” ISPs: smaller (often regional) ISPs Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs France telecome, Tiscali, etc. buys from Sprint Tier-2 ISPs also peer privately with each other, interconnect at NAP Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP

  29. “Tier-3” ISPs and local ISPs (Time Warner, Earthlink, etc.) last hop (“access”) network (closest to end systems) Tier 3 ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP Local and tier- 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP

  30. a packet passes through many networks! Local ISP (taxi) -> T1 (bus) -> T2 (domestic) -> T3 (international) Tier 3 ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP

  31. Networks are complex! many “pieces”: hosts routers links of various media applications protocols hardware, software Question: Is there any hope of organizing structure of network? Or at least our discussion of networks? Organizing the giant structure

  32. ticket (complain) baggage (claim) gates (unload) runway landing airplane routing ticket (purchase) baggage (check) gates (load) runway takeoff airplane routing airplane routing Turn to analogies in air travel • a series of steps

  33. ticket ticket (purchase) baggage (check) gates (load) runway (takeoff) airplane routing ticket (complain) baggage (claim gates (unload) runway (land) airplane routing baggage gate airplane routing airplane routing takeoff/landing airplane routing departure airport intermediate air-traffic control centers arrival airport Layering of airline functionality Layers: each layer implements a service • layers communicate with peer layers • rely on services provided by layer below

  34. Why layering? • Explicit structure allows identification, relationship of complex system’s pieces • Modularization eases maintenance, updating of system • change of implementation of layer’s service transparent to rest of system • e.g., change in gate procedure doesn’t affect rest of system

  35. Protocol “Layers” • Service of each layer encapsulated • Universally agreed services called PROTOCOLS A large part of this course will focus on designing protocols for networking systems

  36. application: supporting network applications FTP, SMTP, HTTP transport: host-host data transfer TCP, UDP network: routing of datagrams from source to destination IP, routing protocols link: data transfer between neighboring network elements PPP, Ethernet, WiFi, Bluetooth physical: bits “on the wire” application transport network link physical Internet protocol stack

  37. Success of Layering • Protocol stack successful in Internet • Internet uses wired physical layer links • Very reliable • BER = 10-8 • What about wireless networks • Very unreliable due to channel fluctuations • Due to co-channel interference • Due to external noise • Does horizontal layering still hold ?

  38. Questions ?

  39. network link physical link physical M M Ht Ht M M Hn Hn Hn Hn Ht Ht Ht Ht M M M M Hl Hl Hl Hl Hl Hl Hn Hn Hn Hn Hn Hn Ht Ht Ht Ht Ht Ht M M M M M M Encapsulation source message application transport network link physical segment datagram frame switch destination application transport network link physical router

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