CSE 422 Computer Networks

1. CSE 422Computer Networks Dr. Abdol-Hossein Esfahanian Computer Science and Engineering Department 3115 Engineering Building

2. Catalog Description • CSE 422:  Computer Networks • Prerequisite: (STT 351 or ECE 280) and (CSE 320 or ECE 331) and (CSE 410 or concurrently) • Description: Computer network architectures and models. Physical media and signaling. Data link protocols. Medium access control. Routing and IP. Transport services including TCP/UDP. Network applications. Local-area and wide-area networks.

3. Course Objectives • Learn the fundamentals of computer networking. • Understand how these fundamentals are applied in real networks, in particular, the Internet. • Understand the relationship between theory and practical design issues in network hardware and software. • Gain an in-depth understanding of how network applications software is supported by underlying protocols. • Learn that computer networks evolve.

4. Course Outline • Introduction • Overview of computer networks • Network architecture models • Network programming interfaces • Physical Layer • Services provided to the data link layer • Theoretical basis for data communication • Bandwidth limitations • Analog and digital transmission • Transmission media • Signaling methods • Multiplexing and switching • Wireless/Mobile communication

5. Course Outline … • Data Link Layer • Services provided to the network layer • Error detection and correction • Stop-and-wait protocols • Sliding window protocols • Medium Access Sublayer • Channel allocation problems • Contention-based protocols • Ethernet architecture • 802.x protocols • Network Layer • Services provided to the Transport layer • Routing algorithms • Internetworking • Internet Protocol

6. Course Outline… • Transport Layer • Services provided to the upper layers • Connection management • UDP, TCP, sockets • Performance issues • Application-level Protocol Standards • Domain name services • Application standards: SNMP, FTP, TELNET, SMTP, NNTP, HTTP • Network Security • Introduction to Cryptography • Public-key algorithms

7. Class Procedures and Policies • Class attendance and participation (5%) • Homework & Labs (15%) • Two exams (25% each) and a final (30%) • Course Grade is based on straight scale; percentages are on total scores possible:

8. Class Procedures …….. • Class notes and other course materials and resources will be available on the course website:http://www.cse.msu.edu/~cse422/ • It is password protected (cse422, tan4me). • Visit this site on regular basis. It is your responsibility!

9. Class Procedures • When attending the class, we ask you to observe a few simple rules which are meant to create a better learning environment. • Come to class on time since we will start lectures right away. • Once class begins, we expect students to pay attention and not read the newspaper or talk, etc. TURN YOUR CELL PHONE OFF. • If you have a question, do not hesitate to ask. • Others are likely to have the same question. • Do not be afraid to ask questions and slow down the pace of the class. If we feel there are too many questions and that we must move on, we will say so, but that should not be taken to mean that the question was ``dumb'' or inappropriate.

10. Class Procedures … • Textbook: Computer Networks, by Andrew Tanenbaum, Fourth Edition. • Students are required to get a copy of this textbook. You will have regular reading assignments from this textbook.

11. Class Procedures … • Instructor: Dr. Abdol-Hossein Esfahanian • Email: esfahanian@cse.msu.edu • Url: http://www.cse.msu.edu/~esfahani/ • Office: 2134EB • Tel: 353-4389 • Office Hours: Wed 1:00pm – 2:00pm, or by appointment, or whenever you can find me.

12. Class Procedures … • Course TA: Bo Wang [wangbo@msu.edu] • Office hours will be on Thursdays 10-12 noon.

13. Class Procedure … • All students will have computer accounts on CSE machines. If your home account is under another domain, then it is your responsibility to have your mail forwarded. • Students are encouraged to work together on homework assignments. However, each student must do his/her write-up. • Unless otherwise specified, exams will be closed-book and will cover material assigned from the texts, notes, handouts, and lectures. For exams only, you are allowed to use an 8½ x 11 note sheet. You should utilize this to write down important formulae, proof techniques etc. • Being caught cheating on ANY aspect of the course is grounds for receiving a grade of 0.0 for the course.

14. Academic Integrity • Academic Integrity is very important in this class and in this university. It is important that students do their work on their own without help from anyone except the instructor or the teaching assistant. Students are permitted to discuss the homework problems with each other. However, the work they turn in must be completely their own. Obviously, no cooperation is permitted during examinations. Students violating this will be dealt with according to the university policy.

15. Important dates • Exam #1 • Thursday Feb 22, 2007 • Exam #2 • Thursday April 5, 2007 • Final: • Thursday May 3, 2007, 10:00-12:00 noon Make note of these dates. Normally there will NOT be any make-up exams.

16. Technologies over the centuries • 18th Century: Mechanical Systems Accompanying The Industrial Revolution • 19th Century: Age of The Steam Engine • 20th Century: Information Gathering, Processing, and Distribution. Examples: • Worldwide Telephone Network • Invention of Radio and TV • Computer Industry • Launching of Communication Satellites

17. 1961: Kleinrock - queuing theory shows effectiveness of packet-switching 1964: Baran - packet-switching in military nets 1967: ARPAnet conceived by Advanced Research Projects Agency 1969: First ARPAnet node operational 1972: ARPAnet demonstrated publicly NCP (Network Control Protocol) first host-host protocol First e-mail program ARPAnet has 15 nodes A brief history of Networking 1961-1972: Early packet-switching principles

18. 1970: ALOHAnet satellite network in Hawaii 1973: Metcalfe’s PhD thesis proposes Ethernet 1974: Cerf and Kahn - architecture for interconnecting networks late70’s: Proprietary Architectures: DECnet, SNA, XNA late 70’s: switching fixed length packets (ATM precursor) 1979: ARPAnet has 200 nodes Cerf and Kahn’s internetworking principles: minimalism, autonomy - no internal changes required to interconnect networks best effort service model stateless routers decentralized control define today’s Internet architecture Networking History (Cont.) 1972-1980: Internetworking, new and proprietary nets

19. 1983: deployment of TCP/IP 1983: smtp e-mail protocol defined 1983: DNS defined for name-to-IP-address translation 1985: ftp protocol defined 1988: TCP congestion control new national networks: Csnet, BITnet, NSFnet, Minitel 100,000 hosts connected to confederation of networks Networking History (Cont.) 1980-1990: new protocols, a proliferation of networks

20. Early 1990’s:ARPAnet decommissioned 1991:NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995) early 1990s: WWW hypertext [Bush 1945, Nelson 1960’s] HTML, http: Berners-Lee 1994: Mosaic, later Netscape late 1990’s: commercialization of the WWW Late 1990’s: est. 50 million computers on Internet est. 100 million+ users backbone links running at 1 Gbps Networking History (Cont.) 1990’s: commercialization, the WWW

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

22. Hosts on the Web

23. Over the past year, the UK added a net increase of 6.1 subscribers per 100 inhabitants. The US added 4.7 subscribers, while Japan added 2.6. The UK's superior growth rate propelled it past the US and Japan to become second only to Canada among G7 countries surveyed in broadband penetration. Source: http://www.websiteoptimization.com/bw/0611/

24. Total Broadband Subscribers • Over the past year, the US has maintained its lead with 31% of total broadband subscribers worldwide. Source: http://www.websiteoptimization.com/bw/0611/

25. Broadband Penetration by Country and Population Density - June 2006 Source: http://www.websiteoptimization.com/bw/0611/

26. Lecture 01Tuesday January 09, 2007

27. Notable • Read Chapter 1 • Read the article Nothing but Net • Forthcoming Topics • What is a computer network • Classification of networks • The layering concept

28. What is a Computer Network? • A computer network is an interconnected collection of autonomous computers. • Two computer are interconnected if they are able to exchange information • Two computer are autonomous if they are capable of operating independently, that is, neither is capable of forcibly starting, stopping, or controlling the other.

29. What is not a Computer Network? • Master/slave systems, in which one computer controls several others • single-host networks, consisting of a single computer with an attached collection of terminals. • Multicomputers, such as the old hypercube, which normally operate as a back-end to a host system. • In terms of (operating) systems, there is some confusion between network systems and distributed systems

30. Network Systems • An interconnection of computers through a communication subnet • The user is aware of the networking of different computers • Network services • remote login • remote file transfer • remote job execution • mail service • Etc,

31. Distributed Systems • A distributed system is a special case of computer network, in which the network of computers appears as a single system to the user, all operations being performed transparently. • Combination of an interconnection of computers and distributed control programs. • Most operations are transparent to the user. • User sees an integrated service environment; distributed system is hidden from the user.

32. Distributed Systems … • Provides location-independent services. • The difference lies with the software rather than hardware. • Allows concurrent processing and greater sharing of resources • Permits development of distributed application programs • Ongoing problems in distributed systems • load balancing • fault-tolerance

33. Applications of Networks • Access to Remote Programs • Simulation • Computer Aided Ed., • Medical Diagnosis • Access to Remote Data Bases • Reservations For Hotels, Airplanes • Home Banking • Automated Newspaper • Automated Library • Access to Information System: (e.g. World Wide Web)

34. Applications of Networks… • Communication Medium • Electronic Funds Transfer System • Electronic Mail • Teleconferencing • Worldwide Newsgroups • International Contacts by Humans • Entertainment Industry • Video On Demand • Multiperson real-time simulation games • Selecting any movie/TV program ever made • Live TV may become interactive with audience

35. Social Issues • Views on politics, religion, …., become distributed • Newsgroups debate sensitive issues • Network operators risk being sued for contents • Rights to free speech may be violated • Anonymous messages can be desirable, but ...

36. Network Classification based on physical size

37. Boundary of the Communication subnet Routers Hosts Network Structure • Communication Subnet (Subnet) • Switching Elements (Routers) • Transmission Lines (Circuits)

38. (b) (c) (a) (d) (e) (f) Types of Design For Subnets • Point-to-Point Circuits (Channels) Some possible topologies for a point-to-point subnet (a) Star (b) Loop (c) Tree (d) Complete (e) Intersecting loops (f) Irregular

39. (c) (a) (b) Types of Design For Subnets… • Broadcast Channels Communication subnet using broadcasting (a) Bus (b) Satellite or Radio (c) Ring

40. Types of Design For Subnets… • Broadcast Subnets May Allocate Channel By: • Static Method • TDMA • Dynamic Methods • Centralized • Decentralized

41. Classification based on switching techniques • Circuit-switched networks • A physical circuit must be established between the two communicating stations before any exchange of information. • Packet-switched networks • No physical circuit is established in advance. • The message is stored and then forwarded at each intermediate node.