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CIS 725

CIS 725. Advanced Computer Networks Lecture 1. Email: gurdip@ksu.edu http://www.cis.ksu.edu/~singh Phone: (785) 532-7945 Fax: (785) 532-7353 Nichols 234C. Books. Computer Networks (not required) Andrew Tanenbaum Lecture notes Papers. Evaluation. Midterm 25% Final 30%

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CIS 725

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  1. CIS 725 Advanced Computer Networks Lecture 1

  2. Email: gurdip@ksu.edu • http://www.cis.ksu.edu/~singh • Phone: (785) 532-7945 • Fax: (785) 532-7353 • Nichols 234C

  3. Books • Computer Networks (not required) Andrew Tanenbaum • Lecture notes • Papers

  4. Evaluation • Midterm 25% • Final 30% • 2-3 homeworks 15% • 3 programming assignments: 30% - SPIN: Promela modeling language - UDP/TCP programming

  5. Course contents • Protocol Design • Network protocols • Issues in network protocol design and implementation • Current research topics • high speed networks, • wireless networks • sensor networks • multimedia networks

  6. Pre-requisites • Undergraduate networking or OS course or equivalent experience

  7. Network • A set of entities connected by communication links - telephone networks - ethernet - internet - hardware circuits

  8. Types of Networks • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Wireless Networks • Home Networks • Internetworks

  9. Local Area Networks • Two broadcast networks (a) Bus (b) Ring Fig. from Tanenbaum 03

  10. Wide Area Networks • Relation between hosts on LANs and the subnet. Fig. from Tanenbaum 03

  11. Wide Area Networks • A stream of packets from sender to receiver. Fig. from Tanenbaum 03

  12. Wireless Networks

  13. Home Networks • Computers (desktop PC, PDA, shared peripherals) • Entertainment (TV, DVD, VCR, camera, stereo, MP3) • Telecomm (telephone, cell phone, intercom, fax) • Appliances (microwave, fridge, clock, furnace) • Telemetry (utility meter, burglar alarm, babycam).

  14. Protocol • A set of rules for communicating - who should speak when - what is the language for communication • What are the common problems - Correctness: deadlocks, livelocks,… - Efficiency • Specification languages

  15. Clayton Tunnel in England (1841) - Best protected railway section • Signalman: • After allowing a train to enter, send “Train in tunnel” • After train leaves the tunnel, send “Tunnel is free” • “Has the train left the tunnel?” “Train in tunnel” “Has the train left the tunnel” “Tunnel is free” • If semaphore failed to turn to red, signalmen is warned by a bell and could then use red and white flags.

  16. First train passes A, and it fails to set the signal to red; • Signalman is warned and he send “Train in tunnel” • Signalman gets the red flag to stop the next train; • Second train is too fast, and passes the green signal; But driver catches a glimpse of the red flag • Signalman is able to stop the third train • Signalman A sends another “Train in Tunnel” message • Signalman A sends “Has the train left the tunnel” • B has no way of knowing what is going on. B sees the train coming out and sends “tunnel is clear” • A now allows third train to enter • The driver of the second train had seen the red flag; he stops in the middle; • To play it safe, he decided to back out; • Collision: 21 people died and 176 injured. Signal, Red flat Tunnel is clear Train in tunnel, Has the train left the tunnel

  17. Attack at 5am

  18. Network SoftwareProtocol Hierarchies • Layers, protocols, and interfaces.

  19. Layered Network Architecture • Each layer takes care of some concerns • Number of layers may vary in different networks • Each layer provides an interface to the upper layer with more functionality added.

  20. Services to Protocols Relationship • The relationship between a service and a protocol.

  21. Layering Example: • Letter in envelope • Address on outside • FedX guy adds addressing information, barcode. • Local office drives to airport and delivers to hub. • Sent via airplane to nearest city. • Delivered to right office • Delivered to right person

  22. Protocol Hierarchies

  23. Problems in a network • Naming • Routing • Congestion control • Error Handling • Flow control • Security • Quality of service

  24. Seven Layer Model (ISO) • Physical Layer: - transmission of raw data over a physical channel - twisted pair, coaxial cables, fiber optics, wireless

  25. Data Link Layer • Physical layer may lose, corrupt, reorder and duplicate data/bits. • Data link layer provides - framing - error free transmission

  26. Network Layer • Provides communication between any pair of nodes in the network; • Provides an illusion that everyone is directly connected to everyone else • Routing • Congestion control

  27. Transport Layer • Connection establishment • Disconnection • Flow control • Sequencing

  28. Session Layer • Establish sessions - a session may have several connections • Recovery

  29. Presentation Layer: - encryption - formatting • Application Layer: - ftp

  30. The TCP/IP reference model

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

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