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Introduction to Computer Networks and Data Communications

This chapter provides an overview of computer networks and data communications, defining key terms, discussing network components, connections, convergence, and network architectures. It also compares the OSI model and TCP/IP protocol suite.

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Introduction to Computer Networks and Data Communications

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  1. Chapter One Introduction to Computer Networks and Data Communications Data Communications and Computer Networks: A Business User's Approach Fifth Edition

  2. Objectives • Define the basic terminology of computer networks • Recognize the individual components of the big picture of computer networks • Outline the basic network connections • Define the term “convergence” and describe how it applies to computer networks • Cite the reasons for using a network architecture and explain how they apply to current network systems Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  3. Objectives (continued) • List the layers of the OSI model and describe the duties of each layer • List the layers of the TCP/IP protocol suite and describe the duties of each layer • Compare the OSI model and TCP/IP protocol suite and list their differences and similarities Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  4. Introduction • Who today has not used a computer network? • Mass transit, interstate highways, 24-hour bankers, grocery stores, cable television, cell phones, businesses and schools, and retail outlets support some form of computer network Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  5. The Language of Computer Networks • Computer network – an interconnection of computers and computing equipment using either wires or radio waves over small or large geographic areas • Local area network – networks that are small in geographic size spanning a room, floor, building, or campus • Metropolitan area network – networks that serve an area of 1 to 30 miles, approximately the size of a typical city Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  6. The Language of Computer Networks (continued) • Wide area network – a large network that encompasses parts of states, multiple states, countries, and the world • Personal area network – a network of a few meters, between wireless devices such as PDAs, laptops, and similar devices • Voice network – a network that transmits telephone signals • Data network – a network that transmits computer data Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  7. The Language of Computer Networks (continued) • Data communications – the transfer of digital or analog data using digital or analog signals • Telecommunications – the study of telephones and the systems that transmit telephone signals • Network management – the design, installation, and support of a network, including its hardware and software Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  8. The Big Picture of Networks • Networks are composed of many devices, including: • Workstations (computers, telephones) • Servers • Network hubs and switches (bridges) • Routers (LAN to WAN and WAN to WAN) • Telephone switching gear Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  9. The Big Picture of Networks (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  10. Communications Networks – Basic Connections • Computer terminal / microcomputer-to-mainframe • Microcomputer-to-local area network • Microcomputer-to-Internet • Local area network-to-local area network • Personal area network-to-workstation Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  11. Communications Networks – Basic Connections (continued) • Local area network-to-metropolitan area network • Local area network-to-wide area network • Sensor-to-local area network • Satellite and microwave • Wireless telephone and wired telephone to network Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  12. Terminal/Microcomputer-to-Mainframe Computer Connections • Predominant form in the 1960s and 1970s • Still used in many types of businesses for data entry and data retrieval • Usually involves a low-speed connection Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  13. Terminal/Microcomputer-to-Mainframe Computer Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  14. Microcomputer-to-Local Area Network Connections • Highly common throughout business and academic environments, and now homes • Typically a medium- to high-speed connection • Computer (device) requires a NIC (network interface card) • NIC connects to a hub-like device Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  15. Microcomputer-to-Local Area Network Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  16. Microcomputer-to-Internet Connections • Popular with home users and small businesses • Often a dial-up modem is used to connect user’s microcomputer to an Internet service provider • Technologies such as DSL and cable modems are replacing modems Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  17. Microcomputer-to-Internet Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  18. Local Area Network-to-Local Area Network Connections • Found in systems that have two or more LANs and a need for them to intercommunicate • A bridge-like device (such as a switch) is typically used to interconnect LANs • Switch can filter frames Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  19. Local Area Network-to-Local Area Network Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  20. Personal Area Network-to-Workstation Connections • Interconnects wireless devices such as PDAs, laptops and notebooks, and music playback devices • Used over short distances such as a few meters Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  21. Personal Area Network-to-Workstation Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  22. Local Area Network-to-Metropolitan Area Network Connections • Used to interconnect companies (usually their local area networks) to networks that encompass a city • High-speed networks with redundant circuits • Metro Ethernet is latest form of metropolitan LAN Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  23. Local Area Network-to-Metropolitan Area Network Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  24. Local Area Network-to-Wide Area Network Connections • One of the most common ways to interconnect a user on a LAN workstation to the Internet (a wide area network) • A router is the typical device that performs LAN to WAN connections • Routers are more complex devices than switches Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  25. Local Area Network-to-Wide Area Network Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  26. Wide Area Network-to-Wide Area Network Connections • High-speed routers and switches are used to connect one wide area network to another • Thousands of wide area networks across North America, many interconnected via these routers and switches Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  27. Sensor-to-Local Area Network Connections • Not all local area networks deal with microcomputer workstations • Often found in industrial and laboratory environments • Assembly lines and robotic controls depend heavily on sensor-based local area networks Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  28. Sensor-to-Local Area Network Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  29. Satellite and Microwave Connections • Typically long-distance wireless connections • Many types of applications including long-distance telephone, television, radio, long-haul data transfers, and wireless data services • Typically expensive services but many companies offer competitive services and rates • Newer shorter-distance services such as Wi-Max Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  30. Satellite and Microwave Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  31. Wireless Telephone Connections • Constantly expanding market across the U.S. and world • Third generation services available in many areas and under many types of plans • Newest generation includes higher speed data transfers (100s of kilobits per second) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  32. Wireless Telephone Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  33. Convergence • An Additional Basic Connection – telephone-to-network • Telephone systems are ubiquitous and now carry more data than voice • Common configuration – telephone connected to POTS • Newer configuration (VoIP) – telephone-to-LAN via gateway or telephone to gateway via DSL/cable Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  34. Network Architectures • A reference model that describes the layers of hardware and software necessary to transmit data between two points or for multiple devices / applications to interoperate • Reference models are necessary to increase likelihood that different components from different manufacturers will converse • Two models to learn: OSI model and TCP/IP protocol suite Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  35. The Open Systems Interconnection (OSI) Model Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  36. The Open Systems Interconnection (OSI) Model (continued) • Application layer • Where the application using the network resides • Common network applications include Web browsing, e-mail, file transfers, and remote logins • Presentation layer • Performs a series of miscellaneous functions necessary for presenting the data package properly to the sender or receiver Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  37. The Open Systems Interconnection (OSI) Model (continued) • Session layer • Responsible for establishing sessions between users • Transport layer • Provides an end-to-end error-free network connection • Makes sure data arrives at destination exactly as it left the source • Network layer • Responsible for creating, maintaining, and ending network connections • Transfers data packet from node to node within network Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  38. The Open Systems Interconnection (OSI) Model (continued) • Data link layer • Responsible for taking the data and transforming it into a frame with header, control, and address information, and error detection code • Physical layer • Handles the transmission of bits over a communications channel • Includes voltage levels, connectors, media choice, modulation techniques Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  39. The Open Systems Interconnection (OSI) Model (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  40. The TCP/IP Protocol Suite Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  41. The TCP/IP Protocol Suite (continued) • Application layer • Equivalent to OSI’s application and presentation layers • Transport layer • Equivalent to OSI’s transport layer • Network (Internet or internetwork) layer • Equivalent to OSI’s network layer • Network access (data link/physical) layer • Equivalent to OSI’s data link and physical layers Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  42. Logical and Physical Connections • A logical connection is one that exists only in the software, while a physical connection is one that exists in the hardware • Note that in a network architecture, only the lowest layer contains the physical connection, while all higher layers contain logical connections Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  43. Logical and Physical Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  44. Logical and Physical Connections (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  45. Network Connections In Action Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  46. The TCP/IP Protocol Suite In Action • Note the flow of data from user to Web browser and back • At each layer, information is either added or removed, depending on whether the data is leaving or arriving at a workstation • The adding of information over preexisting information is termed encapsulation Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  47. The TCP/IP Protocol Suite In Action (continued) Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  48. Summary • Many services and products that we use every day employ computer networks and data communications in some way • Field of data communications and computer networks includes data networks, voice networks, wireless networks, local area networks, metropolitan area networks, wide area networks, and personal area networks Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  49. Summary (continued) • Application areas can be understood in terms of general network connections: • Terminal/microcomputer-to-mainframe computer • Microcomputer-to-local area network • Microcomputer-to-Internet • Local area network-to-local area network • Personal area network-to-workstation • Local area network-to-metropolitan area network • Local area network-to-wide area network • Wide area network-to-wide area network • Sensor-to-local area network • Satellite and microwave • Wireless telephone Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

  50. Summary (continued) • Key concept in networking is convergence • A network architecture, or communications model, places network pieces in layers • Layers define model for functions or services that need to be performed • The International Organization for Standardization (ISO) created the Open Systems Interconnection (OSI) model • OSI model is based on seven layers: application layer, presentation layer, session layer, transport layer, network layer, data link layer, physical layer Data Communications and Computer Networks: A Business User's Approach, Fifth Edition

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