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Computer Networks ECE/CS 438 Fall 2014

Computer Networks ECE/CS 438 Fall 2014. Romit Roy Choudhury Dept. of ECE and CS. Course Logistics. Welcome to ECE/CS 438. Timings: M/W 3 to 4:20pm Location: 1015 New ECE Building Instructor: Romit Roy Choudhury Faculty in ECE & CS. Ph.D from UIUC in Summer, 2006

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Computer Networks ECE/CS 438 Fall 2014

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  1. Computer NetworksECE/CS 438 Fall 2014 Romit Roy Choudhury Dept. of ECE and CS

  2. Course Logistics

  3. Welcome to ECE/CS 438 • Timings: M/W 3 to 4:20pm • Location: 1015 New ECE Building • Instructor: Romit Roy Choudhury Faculty in ECE & CS. Ph.D from UIUC in Summer, 2006 Research in Wireless Networking and Mobile Computing • Office hours: M/W after class or appointment Email me at croy@illinois.edu My office: 263 CSL

  4. Welcome to ECE/CS 438 • Teaching Assistants (TAs) • Fredrick Douglas (CS PhD student) • Office hour: Tue 10-11am, Thu 11-12noon @ 0207 Sielbel • Jatin Ganhotra (CS MS student) • TBD • Junqing Deng (ECE senior) • TBD

  5. Welcome to ECE/CS 438 • Prerequisite: A lot of passion in networking Technically, data structures, probability, and some programming • Further courses: • Advanced Computer Networks • Advanced Wireless Networking • Hot Topics in Mobile Computing • Advanced Distributed Systems • Smartphone Computing and Applications • …

  6. Welcome to ECE/CS 438 • Course Website: https://courses.engr.illinois.edu/cs438/index.html Most course related information will be posted on the website • Please check the course website frequently

  7. Welcome to ECE/CS 438 • Make up classes • Might be necessary due to travel • Would like to schedule on a case by case basis

  8. Welcome to ECE/CS 438 • Grading: • Homework: 20% • Programming Assignments: 25% • 1 mid-term exam: 25% • Final exam: 30% • Programming project may be in groups of 2 • One of the exams is likely to be open book

  9. 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

  10. Course Summary(Very Briefly)

  11. Course information • Course materials: • Text: Computer Networking: A Top Down Approach Featuring the Internet, J. Kurose & K. Ross, Addison Wesley, 3rd ed., 2005, or higher • Class notes/slides • Acknowledgment to Jim Kurose • Some supplementary reading material

  12. 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?

  13. By the time you are finished … You understand variety of factoids and concepts 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, WiFi 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

  14. 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 networking systems (wired Internet/Ethernet and wireless cell/WiFi)

  15. What’s the difference between Communications And Networking

  16. 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

  17. Hello! I am ECE/CS 438

  18. Computer Network Architecture Past, Present, and Future

  19. 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

  20. 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 …

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

  22. And YOU are here

  23. And by “YOU” I mean …

  24. “Cool” internet appliances IP picture frame http://www.ceiva.com/ World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html Internet phones WiFi light bulbs

  25. “Cool” internet appliances Web-enabled toaster + weather forecaster Connected refrigerators

  26. And Of Course people …

  27. InterNetwork • Millions of end points (you, me, and toasters) are connected over a 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

  28. 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

  29. 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

  30. Cables Laid Out in the Oceans Optical Fiber cross-section

  31. Cable Connections carry 95% traffic (rest?)

  32. “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

  33. “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

  34. a packet passes through many networks! Local ISP (taxi) -> T3 (bus) -> T2 (domestic) -> T1 (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

  35. 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

  36. 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

  37. 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

  38. 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., runway delay (wheels up time) depends on clearence of destination runway … doesn’t affect rest of system

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

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

  41. Success of Layering • Protocol stack successful in Internet • Internet uses wired physical layer links • Very reliable • Bit Error Rate (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 ?

  42. Questions ?

  43. 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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