Business Data Communications, Fourth Edition

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Business Data Communications, Fourth Edition

• Chapter 9 Local Area Networks

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Learning Objectives

• Describe the hardware and software used in a
  local area network
• List the topologies used in local area networks
• Specify the differences among CSMA/CD, token
  ring, token bus, ARCnet and AppleTalk

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Learning Objectives

• Describe and show the difference between
  peer-to-peer and server-based networks
• List the differences between wired and wireless
  LANs
• Differentiate between various network operating
  systems

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Learning Objectives

• Describe the advantage of using high-speed LANs
• Define a gateway, bridge, and router in the
  context of local area networks

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Introduction

• Local area networks are located in a limited
  geographic area
• Local area networks are privately owned
• Universities often use local area networks for
  lab environments

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LAN Hardware

• Three main components
• Personal computer
• Network interface card (NIC)
• Transmission medium

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LAN Hardware

• Personal Computer
• Must be compatible with LAN software
• Many different types can be combined on the same
  network
• Need open slot for network interface card
• Workstation or client on the network
• Diskless workstation
• Network computers (NCs)

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LAN Hardware

• Network Interface Card (NIC)
• Link between physical network and PC
• Type of card linked to specific type of LAN
• Transmission Medium
• Guided media
• Unguided media
• Fiber optic often used for backbone network

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LAN Hardware

• LAN Standards
• Institute of Electrical and Electronics Engineers
  (IEEE)
• IEEE 802.x standard

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LAN Topologies

• Topology
• Physical arrangement of the network
• LAN equipment is often moved
• Ring Topology
• Creates a closed loop between the PCs
• Data travels in one direction

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LAN Topologies

• Ring Topology
• Active stations send/receive messages
• Inactive stations cannot respond
• Bypassed by data on the network
• Fiber Distributed Data Interface (FDDI)
• Double ring using fiber-optic cable
• Used for backbone

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LAN Topologies

• Bus Topology
• Single wire connecting all devices
• Terminator used at ends of the cable
• Inexpensive and easy to install
• Ethernet standard uses bus topology

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LAN Topologies

• Star Topology
• Central device connecting all other devices in
  the network
• Point-to-point links used
• Private Branch Exchange (PBX)
• Hub failure is the main problem
• UPS can be used to avoid sudden loss of power

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Protocols

• Ethernet
• Based on bus topology
• 10Base-T connector
• 10Mbps
• Baseband transmission
• 10BaseT (twisted pair)
• Thick Ethernet regular coaxial cable
• Thin Ethernet smaller coaxial cable

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Protocols

• Ethernet
• Fast Ethernet (100 Mbps)
• Gigabit Ethernet (1 Gbps)
• 10 Gigabit Ethernet (10 Gbps)
• Carrier Sense Multiple Access with Collision
  Detection (CSMA/CD)
• MAC protocol
• Contention method
• Originally used for small network, now expanded
  to larger networks.

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Protocols

• Token Passing
• Token string of bits
• Token Ring Network
• Data is added to the token and transmitted
• Free versus busy token
• Uses a MAU, ring is within the MAU
• 4 or 16 Mbps, 100 Mbps in the future
• Fair protocol

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Protocols

• Token Passing
• Token Bus Network
• Token is taken off the network
• Designed like a ring
• ARCnet uses it (2.5 or 20 Mbps)

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Protocols

• Apple Networks
• Appletalk Network
• Original Macintosh network
• CSMA/CA
• 230,400 bps, up to 32 users

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Protocols

• Apple Networks
• AppleShare IP
• Makes Macintosh network more compatible with
  other networks, including the Internet
• Speed depends on server used, up to 500 users
• May be used as Web server

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Types of Networks

• Private Branch Exchange LANs
• Central switch in telephone system
• Failure of central node is greatest threat

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Types of Networks

• Peer-to-Peer LANs
• All workstations are equal
• Hard drives can be shared
• Easy to set up and maintain
• CSMA/CD used
• Windows operating systems have built-in peer
  networks

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Types of Networks

• Server-Based LANs
• Central computer used to store files
• File server
• Files shared among users on LAN
• Files can be stored on server
• Software stored on server, eases maintenance

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Types of Networks

• Server-Based LANs
• Disk server
• Specific amount of disk space allocated to users
• Database server
• Only actual data is returned, not entire file

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Types of Networks

• Wireless LANs
• Rapidly growing technology
• IEEE 802.11a, b, g standards
• Cellular Digital Packet Data (CDPD)
• Cellular radio technology

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Types of Networks

• Wireless LANs
• Spread Spectrum Radio (SSR)
• Modulated radio signal
• Eliminates interference and eavesdropping
• Frequency-hopping spread spectrum (FHSS)
• Direct-sequence spread spectrum (DSSS)
• Infrared Transmission

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LAN Software

• Network Operating System
• Does not always replace the operating system
• Novell NetWare
• Dedicated server
• Supports Ethernet or Token ring
• Uses disk caching for file access
• Frequently access files stored in memory for
  quicker access
• NetWare Directory Services (NDS)

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LAN Software

• LANtastic
• Peer network
• Ethernet or Token ring
• PCs defined as servers or workstations
• Windows NT/2000/2003
• Does not need DOS
• NT Server and NT Workstation
• 2000 Server and 2000 Advanced Server
• Server 2003

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LAN Software

• Linux
• Similar to UNIX
• Open source code
• Alternative to high-end NOSs

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High-Speed LANs

• Fast Ethernet
• 100 Mbps
• Uses CSMA/CD, same as Ethernet
• Used for links between servers
• Gigabit Ethernet
• 1 Gbps
• Backbone for high volume networks
• 10 Gigabit Ethernet

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Connecting Networks

• Repeaters
• Cable length without repeaters limited to 1,641
  feet by IEEE 802.3 standard
• LAN can be extended by four segments using
  repeaters

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Connecting Networks

• Bridge
• Connects two LANs using the same protocol
• Operates at data link layer
• Internal bridge
• Adapter card
• External bridge
• Separate PC
• Used on high-volume LANs

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Connecting Networks

• Routers
• More sophisticated than a bridge
• Operate at network layer
• Can be used to isolate a portion of the LAN
• Gateways
• Connect networks using different protocols
• Can be used to connect a LAN to a WAN

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Summary

• LANs used for sharing hardware and software
• Personal computers, adapter cards, and cables
  make up the LAN
• LANs use ring, bus, and star topologies
• Unique protocols are used in LANs CSMA/CD,
  token bus, token ring

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Summary

• Control of LANs are different in PBX, peer, and
  server-based networks
• Software is needed to run the network
• Connections between networks can be made using
  repeaters, bridges, routers, and gateways

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Chapter 9 Complete