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Chapter 11

Chapter 11. Network Fundamentals. Agenda. Definition Classification Information Routing Connection Telecommunication software Architecture. Definition. Network Backbone network. Classification. Topology Ownership Geography Transmission. Network Topology. Star Hierarchical Mesh

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Chapter 11

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  1. Chapter 11 Network Fundamentals

  2. Agenda • Definition • Classification • Information Routing • Connection • Telecommunication software • Architecture

  3. Definition • Network • Backbone network

  4. Classification • Topology • Ownership • Geography • Transmission

  5. Network Topology • Star • Hierarchical • Mesh • Bus • Ring • Hybrid

  6. Star Network • Circuits • Point-to-point, multipoint, or combination • Pros • Expand • Implement • No limit to no. and length of arms • Cons • Single point of failure • Overload of mater during peak traffic

  7. Hierarchical Network • Tree structure with a root • pro • No single point of failure • Divisional communications and processing

  8. Mesh Network • Web structure • Usage • Public telephone system • Pro • Alternative communication route • Virtually fail-safe • Con • Line cost

  9. Bus Network • Usage • High speed, short distance between nodes • Local area network • Pros • Independent between nodes • High reliability • Cons • Limited number of attached device • Hard to locate the problems

  10. Ring Network • Usage • Nodes are relatively close together • Pros • Less attenuation • Error control • Network management • Cons • Failing of a node • Two opposite direction channels

  11. Hybrid Networks • Usage • Connecting different networks • Pro • Communication between different networks • Con • Conversion device and costs

  12. Network Ownership • Private networks • Public networks • Valued added networks

  13. Private networks • Full control • Special needs • Expense

  14. Public networks • Controlled by carriers • Regulated by government • Inexpensive

  15. Valued Added Networks • Public network • Functions • Code translation • Speed conversion • Store message and delivery • Examples • Telex • SWIFT • SITA (airline) • IVAN (insurance)

  16. Networks by Geography • Wide area network (WAN) • Metropolitan area network (MAN) • Local area network (LAN)

  17. Wide Area Networks • Public Switched Telephone Network (PSTN) • Provided by carriers • Inexpensive • High quality service for infrequent users

  18. Metropolitan Area Networks • IEEE 802.6 • Distance up to 30 miles • High bandwidth for data, voice, and video • T1, T3, or fiber optic cable • Private own or dark fiber supplied by MAN provider

  19. Network Transmission Types • Circuit Switching • Packet data networks (PDNs) • Frame relay • Asynchronous transfer mode: ATM (Cell relay)

  20. Circuit Switching • Temporarily Dedicated communications line between two stations for transmission • Efficient for constant voice and video transmission • Inefficient for non-constant data transmission

  21. Packet Data networks (PDNs) - I • Packet • Less than 1,000 bytes • PAD (packet assembly/disassembly) • Address and control fields for error checking • Connection types • Switched virtual circuit: dial-in (switched) • Permanent virtual (leased) circuit: heavy & frequent traffic • Datagram: short message, no error checking

  22. Packet Data networks (PDNs) - II • Standard • ITU-T’s X.25 • Between terminal and PDN on public network • ITU-T’s X.75 • Interface between two PDNs • Examples • USA: APARANET, Telenet, Tymnet, General Electric Information Services (GEIS)

  23. Packet Data networks (PDNs) - III • Characteristics • Reliable service • Nationwide service • Lower error rates • Variety of transmission speeds • Cost-effectiveness

  24. Frame Relay • Acknowledge only by final node • Benefits • Variable-length frames (1- 64,000 bytes) • Reduce overhead • More efficient transmission • Problems • Circuit congestion • Committed information rate (CIR) & port speed for service guarantee & discarding frames

  25. ATM (Cell-Relay) • Asynchronous transfer mode (ATM) • Cells : fixed length packets of 53 bytes • 45Mbps (T3) or higher speeds • Pros • High throughput, low delay, transparency, flexibility, and high capacity • Con • Expensive

  26. ATM Services • Realtime service • Constant bit rate (CBR) for telephone and videoconference • Realtime variable bit rate (rt-VBR) for compressed video • Non-realtime service • Non-realtime variable bit rate (nrt-VBR) for airline reservation or financial transaction • Available bit rate (ABR) for LAN-to-LAN • Unspecified bit rate (UBR) for TCP-based traffic

  27. Routing Message • Connection-oriented routing & connection less routing • Broadcast routing • Centralized routing • Distributed routing • Static and dynamic routing

  28. Broadcasting Routing • CSMA/CD • Pros and cons • Simplest • For small network • Not for moderate to heavy traffic

  29. Centralized Routing • Star or hierarchical networks • IBM’s SNA networks • Using static routing table in one central computer • Pros and cons • Simple • Potential performance bottleneck • Single point of failure

  30. Distributed Routing • Routing tables on several nodes • Pros and cons • No single point of failure • Routing table update problem • Complicated to implement

  31. Static and Dynamic Routing • Static routing • Predetermined route • Simple but inflexible • Dynamic routing • Use routing algorithms to evaluate traffic volumes, error rates, and other conditions for the best path • Flexible but high overhead and complicated to implement

  32. Interconnecting Networks • Transmission control protocol/ internet protocol (TCP/IP) • Internet • Intranet & extranet

  33. Transmission Control Protocol • OSI transport layer • Connection oriented • Functions • Assemble and reassemble message packets • Reliable & error free message delivery • Urgency or priority • Security (encryption)

  34. Internet Protocol • OSI network layer • Routing & addressing messages to other networks • Connectionless operation • IPv6 • 128 bits for addressing • Quick and efficient

  35. TCP/IP Application protocols • File Transfer Protocol (FTP) • Tenet • Simple Mail Transfer Protocol (SMTP) • Multipurpose Internet Mail Extensions (MIME) • Remote Procedure Call (RPC) • Simple Network Management Protocol (SNMP)

  36. Internet • Usages • Electronic mail, remote log in to various computers, discussion groups, information search and retrieval • Electronic mail (e-mail) • Edu, com, org, gov, mil, net • Web servers & web browsers • Hypertext Markup Language (HTML) • Uniform Resource Locator (URL) • Home page • Internet service provider (ISP)

  37. Intranets & Extranets • Intranets • Extranets • Benefits: fast information transmission • Problems: security & privacy

  38. Connect Network to Computer • Methods • Direct connection between circuit and computer • Small network • Low cost • Cycle stealing • Network interface card • Use a front-end processor: telecommunication control unit or transmission control unit • Large host computer • Better utilize computer resources

  39. Front-end Processors (FEPs) • Types • Hardware (interface or port): speed • Software ( network control program NCP): flexible

  40. FEPs - Functions • Circuit control • Assembly messages • Message queuing or storing • Error control • Administration functions

  41. Functions of Telecommunication Softwarein Host Computer • Security • Buffer management • Routing a message to a program • Queuing messages • Scheduling application program • Providing continuity between part of a transaction • Message formatting • Checkpoint/restart • Preventing messages from lost or duplicated

  42. Software for Network Management • Control and monitor the network status • Start/stop network, terminal, and line • Performance • Log network operation • Display network data

  43. Manufacturers’ Architectures • IBM’s System Network Architecture (SNA) • Digital Equipment Corporation’s Digital Network Architecture (DNA)

  44. IBM’s SNA Concepts • Physical units • Logical units • Sessions • Network addressing units (NAUs) • Data link protocols • SNA software • Network Control program (NCP) • Virtual Telecommunications Access Method

  45. SNA Physical Units • Terminals (1) • Cluster controllers (2) • Front-end processors (4) • Host computers (5)

  46. SNA Logical Units • People • Application programs

  47. SNA Sessions • Types • Terminal-to-terminal • Terminal-to-program • Program-to-program • Modes • Interactive • Batch • Multiple simultaneous

  48. SNA Network Addressable Units • Physical units • Logical units • Address: 24 bits

  49. SNA Data Link Protocols • Synchronous Data Link control (SDLC) • Binary Synchronous Communications (BISYNC or BSC) • X.25

  50. System Network Architecture • Physical control • Physical and electrical connections • Transmission codes • Voltages • Data link control • Format • Reliability • Path control • Routing information • Transmission control • Security & compression • Data flow control • Flow control • Presentation services • Format • Transaction services • Coordinating application software

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