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CSE 5300: Advanced Computer Networks

CSE 5300: Advanced Computer Networks. Bing Wang Computer Science & Engineering Department Fall 2008. Instructor: Bing Wang, bing@engr.uconn.edu Office: ITEB 367 Lecture: 3:30-4:45pm, TuTh, E2 322 Office hours: by appointment. Course info. Wireless networks, basics & advanced topics

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CSE 5300: Advanced Computer Networks

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  1. CSE 5300: Advanced Computer Networks Bing Wang Computer Science & Engineering Department Fall 2008

  2. Instructor: Bing Wang, bing@engr.uconn.edu Office: ITEB 367 Lecture: 3:30-4:45pm, TuTh, E2 322 Office hours: by appointment Course info

  3. Wireless networks, basics & advanced topics a second course: i.e., assumes a first course difference & synergybetween wired & wireless networks foundational material: longer life mix of theory and practice Course goals

  4. Wireless networks • Wireless LAN, ad-hoc network, wireless mesh, sensor network Internet

  5. Other wireless networks • Cellular networks • Underwater sensor networks • Vehicular ad-hoc works • Delay/disruption tolerant networks (DTN) • Pocket switching networks • Turtle networks • Zebra networks • Diesel networks

  6. Striking differences between Internet & wireless networks? • Wireless (prone to error; interference) • Mobility • Easy to set up • Of less scale • Of various forms • w/ or w/o dedicated infrastructure • PCs, PDAs or embedded devices • at edge or not at edge

  7. physical layer basics MAC routing network simulation, performance analysis network measurement/management mobility security common themes: randomization, indirection, scalability, optimization Course topics

  8. class www site: www.engr.uconn.edu/~bing/cse5300 textbook: none papers, all posted on www site prereq: previous course in networking some knowledge of probability, optimization theory, algorithms workload: 3 paper critics 2 written homeworks 1 programming assignment (on using ns-2) 1 semester-long project Course mechanics

  9. Grading • Paper critics (10%) • 3 papers • Homework (30%) • Semester-long project (60%) • Goal: hand-on experiences through a well-defined research problem • Team of 2 students • Topic (your background, preference) • Fill in background survey • Proposal (due 5th class) • Midterm report/presentation (17th class) • Final report/presentation (last class)

  10. Goals: review key topics from intro networks course equalize backgrounds identify remedial work ease into course Overview: overview error control flow control congestion control routing addressing synthesis: “a day in the life” control timescales Part 0: Networking review

  11. network edge: millions of end-system devices: pc’s workstations, servers PDA’s, phones, toasters running network apps network core: routers, switches forwarding data packet switching communication links fiber, copper, radio, … What’s Internet: “nuts and bolts” view router workstation server mobile local net regional net company net

  12. Wireless networks: “nuts and bolts” view • Wireless nodes • Wireless links • Wireless routers (dedicated or not) • Edge and core?

  13. a human protocol and a computer network protocol: Hi TCP connection req. Hi TCP connection reply. Get http://www.cse.uconn.edu/index.html Got the time? 2:00 <file> time What’s a protocol?

  14. human protocols: “what’s the time?” “I have a question” introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols: machines rather than humans all communication activity in computer networks governed by protocols What’s a protocol? protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

  15. handshaking: setup (prepare for) data transfer ahead of time Hello, hello back human protocol set up “state” in two communicating hosts TCP - Transmission Control Protocol Internet’s connection-oriented service TCP service[RFC 793] reliable, in-order byte-stream data transfer loss: acknowledgements and retransmissions flow control: sender won’t overwhelm receiver congestion control: senders “slow down sending rate” when network congested Data transport: connection-oriented service

  16. UDP - User Datagram Protocol [RFC 768]: Internet’s connectionless service unreliable data transfer no flow control no congestion control App’s using TCP: HTTP (WWW), BitTorrent (file transfer), Telnet (remote login), SMTP (email) App’s using UDP: streaming media, teleconferencing, Internet telephony Data transport: connectionless service

  17. Data transport in wireless networks • No consensus • Use TCP • Problematic: loss may not be due to congestion • Use UDP • No notion of transport protocol

  18. edge, core, links protocols We have seen “pieces” of network How do we talk about “structure” of network and its architecture? • layered architecture • structure allows identification, relationship of complex system’s pieces: layered reference model for discussion • layer N builds on services provided by layer N-1 • layer N provides service to layer N+1 • physical topology, interconnection

  19. application: supporting network applications ftp, smtp, http, BitTorrent 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 physical: bits “on the wire” application transport network link physical Internet protocol stack

  20. network link physical application transport network link physical application transport network link physical application transport network link physical application transport network link physical data data Layering: physical communication

  21. Layering in wireless networks • No consensus • Layers • Physical layer • MAC layer • routing • Cross-layer design • Blur boundaries

  22. roughly hierarchical at center: “tier-1” ISPs (e.g., UUNet, BBN/Genuity, Sprint, AT&T), national/international coverage treat each other as equals NAP Tier-1 providers also interconnect at public network access points (NAPs) Tier-1 providers interconnect (peer) privately Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP

  23. “Tier-2” ISPs: smaller (often regional) ISPs Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs NAP 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 is customer of tier-1 provider 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

  24. “Tier-3” ISPs and local ISPs 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 NAP 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

  25. a packet passes through many networks! Tier 3 ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP NAP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Try a traceroute! Tier 1 ISP Tier 1 ISP

  26. Architecture of wireless networks • Varies • Completely flat • Some form of hierarchy • Things may change as wireless networks grow larger

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