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Introduction

Introduction. About the course. Lecturer: Weiqiang Sun ( 孙卫强 ) TA: Kai Kang( 康凯 ) Requirements and grading: One problem set each week (20%) Class participation (15%) Final exam (65%) Textbook Bertsakas & Gallager , Data Networks, 2 nd Edition

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Introduction

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  1. Introduction

  2. About the course • Lecturer: Weiqiang Sun (孙卫强) • TA: Kai Kang(康凯) • Requirements and grading: • One problem set each week (20%) • Class participation (15%) • Final exam (65%) • Textbook • Bertsakas & Gallager, Data Networks, 2nd Edition • Course website (lecture notes, problem set & solutions etc.) • http://front.sjtu.edu.cn/datacomm/

  3. Content coverage • This course will cover fundamental aspects of data network analysis and design • Architecture • Network layering • Protocols • Point-to-point • End to end • Multi-access • Algorithms • Error recovery • Routing • Flow control • Analysis tools • Queueing theory • Probabilistic modeling

  4. Course syllabus

  5. Guest lectures (tentative)

  6. The history of Internet • 1946, first appearance in science fiction: A logic named Joe • 1969, interconnection of two nodes, later became ARPANET • 1974, TCP Protocol became an RFC and the first use of term “Internet” • 1976, X.25 became a CCITT (later ITU-T) standard • 1978, International packet switched service in US and Europe • 1981, X.25 based network grew from Europe and US to Canada, HK and Australia • 1983, first TCP/IP base wide-area network started to operate, NSFNET started construction in 1985 • 1989, commercial mail services were available on NSFNET • 1991, WWW was publicized at CERN: European Organization for Nuclear Research • 1996, the use of internet had become commonplace

  7. The history of Internet • 1946, first appearance in science fiction: A logic named Joe • 1969, interconnection of two nodes, later became ARPANET • 1974, TCP Protocol became an RFC and the first use of term “Internet” • 1976, X.25 became a CCITT (later ITU-T) standard • 1978, International packet switched service in US and Europe • 1981, X.25 based network grew from Europe and US to Canada, HK and Australia • 1983, first TCP/IP base wide-area network started to operate, NSFNET started construction in 1985 • 1989, commercial mail services were available on NSFNET • 1991, WWW was publicized at CERN: European Organization for Nuclear Research • 1996, the use of internet had become commonplace

  8. Network applications • E-mail • The World Wide Web • Remote access • Collaboration • File sharing (FTP, BT etc) • Streaming (PPLive, IPTV etc) • Voice telephony (VoIP) • And much more….

  9. Network coverage areas • Wide Area Networks (WAN) • Large footprint, usually country scale, or inter-country scale, 1000KM and more • Use leased line/circuit switching • Metro Area Networks (MAN) • Medium footprint, in a city (metropolitan), 50-100KM • Provides connectivity for LAN in a city • Local Area Networks (LAN) • Small span, in a building or office, ~100M • Direct high speed connection • Home Area Networks (HAN) • Personal Area Networks (PAN) • Storage Area Networks (SAN) • …

  10. Switching techniques • Circuit switching • Dedicated resources • Low efficiency • Higher Quality of Service • Packet switching • Shared resources • Can be used to implement virtual circuits • High efficiency • Prone to congestion and packet loss

  11. Network footprints and switching techniques • Wide Area Networks (WAN) • Metro Area Networks (MAN) • Local Area Networks (LAN) • Home Area Networks (HAN) • Personal Area Networks (PAN) • Storage Area Networks (SAN) • … Circuit switching Packet switching

  12. The layered network model – OSI reference model Application Application Presentation Presentation Session Session Transport Transport Network Network Network Network Data Link Control DLC DLC DLC DLC Data Link Control Physical Interface PHY PHY PHY PHY Physical Interface

  13. The OSI reference model in the context of broadband access – an example Your PC Your friend’s PC Application Application Presentation Presentation Session Session Transport Transport W-less router …. Network Network Network Network DSL Modem Data Link Control DLC DLC DLC DLC DLC Data Link Control Physical Interface PHY PHY PHY PHY PHY PHY Physical Interface

  14. The layered network model – OSI reference model Peer communications Application Application Inter-layer communications Presentation Presentation Session Session Transport Transport Network Network Network Network Data Link Control DLC DLC DLC DLC Data Link Control Physical Interface PHY PHY PHY PHY Physical Interface

  15. The physical layer • Responsible for transmission of bits over a link • Wireline link, such as twisted pair, fiber optics, serial lines etc • Wireless link, such as satellite link, free space optics, microwave etc • Modulation and de-modulation (MODEM) • Mapping the bits from high layer to signals and the reverse • Modes of operation • Synchronous, intermittent synchronous, and asynchronous • Can incur transmission errors • Noise, power loss etc • Can induce transmission delay • The speed of light (EM wave)

  16. The data link control layer • Responsible for error-free transmission of bits across a point-to-point link • Realizes a reliable “virtual” link • Re-transmit, or drop packet if some error occurs • Framing, error detection and correction • Sometimes in a shared media, is also responsible for contention resolution/access control • e.g. in a wireless radio network • The MAC sublayer

  17. The Network layer • Routing and flow control in the network (network wide) • One network layer process on each node • Route the packets to the proper outgoing DLC, or to up layer (at destination) Network layer A node DLC Layer Link 1 DLC Layer Link 1 DLC Layer Link 1

  18. The transport layer • Break messages into packets and reassemble • Packet of size suitable for network layer • Multiplex sessions with same source/destination nodes • Re-sequence packets at destination • Recover from packet loss or failures • Provide end-to-end flow control

  19. Other layers • Presentation layer • Provides character code conversion, data encryption, data compression, etc. • Session layer • Obtains virtual end to end message service from transport layer • Provides directory assistance, access rights, billing functions, etc. • Standardization has not proceeded well here, since transport to application are all in the operating system and don't really need standard interfaces

  20. The Internet model FTP, HTTP, SMTP… application application TCP/UDP protocol transport transport IP protocol IP protocol IP IP IP Data link and lower layer Ethernet Token ring Data link and lower layer Ethernet Ethernet Token ring

  21. Encapsulation User data “hi” application “hi” TCP data transport “hi” IP packet IP “hi” Ethernet Frame Data link and lower layer “hi” Ethernet

  22. The “Hi” example Frame header / trailer IP header TCP header Hi

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