COMP 6005 An Introduction To Computing

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COMP 6005 An Introduction To Computing

• Session Four Internetworking and the World Wide
  Web
• Networks

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Objectives

• Describe how computers communicate with each
  other via networks
• Distinguish between the different types of
  networks
• Compare and contrast network architectures

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Definition

• A network is a connection between two or more
  computers
• A network is a collection of computers and
  devices connected via communication devices and
  transmission media (Discovering Computers 2005)

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Types of Networks

• Personal Area Networks (PAN)
• Local Area Networks (LAN)
• Campus Area Network (CAN)
• Metropolitan Area Network (MAN)
• Wide Area Networks (WAN)
• Wireless Local Area Network (WLAN)

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Personal Area Network

• Used for communication among computer devices
  (including telephones and PDAs) close to one
  person
• Reach is typically a few meters
• Can be used for communication among the personal
  devices themselves (intrapersonal communication),
  or for connecting to a higher level network and
  the Internet (via uplink)

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Local Area Network

• Covers a local area, like a home, office, or
  group of buildings
• Do not require leased telecommunication lines
• Much higher data rates than WANs
• Have smaller geographic range than WANs

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Campus Area Network

• Made up of an interconnection of LANs within a
  limited geographical area
• Can be considered one form of a metropolitan area
  network, specific to an academic setting
• For a university campus-based CAN, network is
  likely to link a variety of campus buildings
  including academic departments, the university
  library and student residence halls
• Larger than a local area network but smaller than
  a wide area network

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Metropolitan Area Network

• Large, usually spanning a city
• Typically use wireless infrastructure or optical
  fiber connections to link their sites
• Might be owned and operated by a single
  organization usually will be used by many
  individuals and organizations
• Will often provide means for internetworking of
  local networks

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Wide Area Networks

• Covers a broad geographical area
• Largest and most well-known example is the
  Internet
• Used to connect LANs together, so that users and
  computers in one location can communicate with
  users and computers in other locations
• WANs are most often built using leased lines

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Wireless Local Area Networks

• The linking of two or more computers without
  using wires
• Uses radio communication to accomplish the same
  functionality that a wired LAN has

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Types of Networks

• Bus
• Ring
• Star -
• http//www.webopedia.com/quick_ref/topologies.asp

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Bus Network

• Consists of single central cable to which all
  computers and other devices connect
• Data, instructions and information is transmitted
  in both directions
• Computers and devices can be attached and
  detached at any point without affecting the rest
• Failure of one device does not affect the others

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Ring Network

• Cable forms a closed loop with all computers and
  devices arranged along it
• Data travels from device to device around the
  ring in one direction
• If one device fails, all devices after it cannot
  function
• Can span a larger distance than a bus more
  difficult to install

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Star Network

• All computers and devices (nodes) connect to a
  central device (hub)
• All data transmitted passes through the hub
• Easy to install and maintain nodes added and
  removed with little or no disruption to network
• If node fails, no affect on other nodes if hub
  fails, entire network is inoperable

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Network Protocols

• Ethernet
• Token Ring
• TCP/IP
• 802.11

• Bluetooth
• IrDA
• RFID
• WAP

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Assignment

• Describe the following technologies
• TCP/IP
• 802.11
• Bluetooth
• IrDA
• RFID
• WAP

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Ethernet

• Most widely-installed LAN technology
• Typically uses coaxial cable or special grades of
  twisted pair wires also used in wireless LANs
• Uses a bus or star topology and supports data
  transfer rates of 10 Mbps
• Newer version (called 100Base-T or Fast Ethernet)
  supports rates of 100Mbps
• Newest version, Gigabit Ethernet, supports data
  rates of 1 Gbps

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Token Ring

• All computers connected in a ring or star
  topology and a bit- or token-passing scheme is
  used in order to prevent the collision of data
  between two computers that want to send messages
  at the same time
• Physically, token ring network is wired as a
  star, with 'hubs' and arms out to each station
  and the loop going out-and-back through each
• Second most widely-used protocol on LANs after
  Ethernet

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Network Architecture

• Peer-to-peer
• Client/server

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Peer-to-peer

• Each workstation has equivalent capabilities and
  responsibilities
• Generally simpler than client/server usually do
  not offer same performance under heavy loads
• Network itself relies on computing power at the
  ends of a connection rather than from within the
  network itself

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Client/server

• Each computer or process is either a client or
  server
• Servers dedicated to managing disk drives,
  printer, network traffic
• Clients users run applications rely on servers
  for resources such as files, devices and
  processing power
• Sometimes called two-tier architectures

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Two-tier

• User interface runs on the client database is
  stored on the server
• Actual application logic can run on either client
  or server
• Newer three-tier architecture introduces middle
  tier for the application logic

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Links

• Reference
• Whatis.com, http//www.whatis.com
• Webopedia.com, http//www.webopedia.com
• Wikipedia.com, http//www.wikipedia.com
• Discovering Computers 2005 by Shelly, Cashman and
  Vermaat