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212F (Sept 2008) Network Programming and Design

212F (Sept 2008) Network Programming and Design. Lecture 2 (Network Basics & Architecture) Course Coordinator : Dr. Philip Tsang Tutor : Mr. Ken Ho, Mr. Lee, Bo-sing (Joe) URL of my TA’s teaching website : http://ucourse.ouhk.edu.hk/~t441051/ct212.

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212F (Sept 2008) Network Programming and Design

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  1. 212F (Sept 2008) Network Programming and Design Lecture 2 (Network Basics & Architecture) Course Coordinator : Dr. Philip Tsang Tutor : Mr. Ken Ho, Mr. Lee, Bo-sing (Joe) URL of my TA’s teaching website : http://ucourse.ouhk.edu.hk/~t441051/ct212 Link of today’s lecture: http://labsupport.no-ip.org/~opms/temp/ppt2swf.html CT212 Course Team

  2. Agenda • Further Course Info • Syllabus • Material • Assessment • Support • Your UNIX account Lecture 2 • Your Internet/Network/ mobile phone experiences {Video capture • Convert PPT to flash web page CT212 Course Team

  3. Your Unix Account • Server: labsupport.no-ip.org • IP address (how do you find out?) • Login s+first 7 digits • Passwd : ptsang123 • Change your passwd after you login using secure telnet such as putty.[ See Lab2.1 of your lab book] CT212 Course Team

  4. Lecture 2 • Objective of Lecture 2 • Lecture 2 • Network classification : LAN & WAN • Layering network model – OSI & TCP/IP • LAN topology • Network Transport method : Ethernet & Token ring • Components of network • Cable concentrating devices • Transmission media • NOS (to be discussed in Tutorial 2) • Introduction to E-commerce & network games CT212 Course Team

  5. Objectives of Lecture 2 • Identify building blocks (components) of network • Describe how these building blocks can be glued together • Explain the layers of the OSI model, & describe specific networking services within each layer of the OSI model. • Describe the physical characteristics of coaxial cable, STP, UTP, fiber-optic & atmospheric transmission media. • Discuss the Ethernet & Token Ring network transport systems • Describe the basic topologies, & explain the benefits & uses of different topologies • Describe the features of different network devices CT212 Course Team

  6. Network classification (1) • Definition of computer network • a group of computers & networking devices that are connected by some type of transmission media. The computers can communicate, provide or access shared resources, with the help of some networking S/W. • What does a network provide? • Entertainment (network games) • E-commerce • Share resources & data (storage, print, file,..) • Provide internet services (email, web, dns, ics, ..) • Management/Workflow automation • Online discussion • Video conference…… CT212 Course Team

  7. Network classification (2) • Classification of networks by size • LAN (Local Area Network) • within an office or building • usually private • WAN (Wide Area Network) • across city, country or even international • Connected through public data network provided by carrier • Nowadays, most LANs or WANs are connected to INTERNET CT212 Course Team

  8. Network classification (3) • Classification of networks by transmission media: • Wired network • Transmission media is cable • Eg. Cat5. UTP, optic fiber, etc • Wireless network • Transmission media is through air • Eg. RF or Infrared CT212 Course Team

  9. Layered network model(1) • In order to allow 2 computers to communicate, exchange data, share/access resource via a network, these 2 computers must follow a number of rules. The rules are so many and complicated. These rules are called networking protocols. • We need a method/mechanism to develop & handle these rules. • So, a layered network model is required for computer networking. • There are 2 networking models – OSI & TCP/IP CT212 Course Team

  10. Layered network model(2) • Logical view of a layered network model • Network is divided into a number of layers • Lowest layer is numbered as 1, higher layer is numbered with larger number • Layer N (Boss) request service, layer N-1 (employee) provide service • Each layer is ignorant about implementation of other layers • Each layer only knows the interface (SAP) to directly lower or upper layer • Peer to peer protocol (refer to next slide) CT212 Course Team

  11. Layered network model(3) • Peer-to-Peer Protocol CT212 Course Team

  12. Layered network model(4) • Advantages • Simplify complexity of network design & implementation • Easy for human to discuss & analyze • Allow interoperability between products from different vendors • Change of any layer is transparent to other layers • Implementation of any layer is independent of other layers CT212 Course Team

  13. Layered network model(5) – OSI (1) • OSI model • 7 layers – Application, Presentation, Session, Transport, Network, Data link, Physical layer • “ A Police Stole Three New Dupoint Products” • Well-defined • More restrictive in layering structure • Transport layer can use different protocols eg. SPX for Netware • Usually as a reference point for discussion use or academic research. Seldom implemented CT212 Course Team

  14. Layered network model(6) – OSI (2) • Layer 1 - The Physical Layer • Deal with the physical, electrical characteristics of the physical medium. • Connectors, pin assignment, electrical currents, encoding, and light modulation • Eg. V.35, V.24, RJ45, Ethernet, 802.3, 802.5, FDDI, NRZI, NRZ, etc. • Layer 2 - The Data Link Layer • Define how a packet is transmitted as bits/ frames of bits • Perform error detection/correction by CRC • Eg. Frame Relay, HDLC, PPP, FDDI, ATM, Ethernet, Token ring, etc. CT212 Course Team

  15. Layered network model(7) – OSI (3) • Layer 3 - The Network Layer • defines logical addressing for identifying any node • Packet forwarding • Fragmentation at sender or intermediate node • reassembly at destination • Eg. IP, IPX, AppleTalk DDP • Layer 4 - The Transport Layer • Provide end-to-end transmission of data • Perform error recovery • Perform flow control • Perform congestion control • Reordering of the incoming data stream when packets arrive out of order • Connection-oriented or connectionless-oriented • Eg.TCP, UDP, SPX CT212 Course Team

  16. Layered network model(8) – OSI (4) • Layer 5 - The Session Layer • Define how to start, control, and end conversations (called sessions) • Control and management of multiple bidirectional messages • The session layer creates ways to imply which flows are part of the same session and which flows must complete before any is considered complete, • E.g. ATM machines • NFS, NetBios names CT212 Course Team

  17. Layered network model(9) – OSI (5) • Layer 6 - The Presentation Layer • Define data format • Perform data format translation • Perform data encryption and decryption • For example, binary or ASCII transfer of FTP, Character Sets translation in RDBMS • TIFF, GIF, JPEG, ASCII, EBCDIC, MPEG, MIDI, MP3, Big5, GB • Layer 7 - The Application Layer • Interface between application & user • Specify protocols used between applications (communications capabilities) • Eg. FTP, http, Telnet, NFS, SMTP, SNMP CT212 Course Team

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