Business Data Communications, Fourth Edition

1. Business Data Communications, Fourth Edition Chapter 9: Local Area Networks

2. 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 Chapter 9: Local Area Networks 2

3. 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 Chapter 9: Local Area Networks 3

4. Learning Objectives • Describe the advantage of using high-speed LANs • Define a gateway, bridge, and router in the context of local area networks Chapter 9: Local Area Networks 4

5. 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 Chapter 9: Local Area Networks 5

6. LAN Hardware • Three main components • Personal computer • Network interface card (NIC) • Transmission medium Chapter 9: Local Area Networks 6

7. 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) Chapter 9: Local Area Networks 7

8. 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 Chapter 9: Local Area Networks 8

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10. LAN Hardware • LAN Standards • Institute of Electrical and Electronics Engineers (IEEE) • IEEE 802.x standard Chapter 9: Local Area Networks 10

11. 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 Chapter 9: Local Area Networks 11

12. 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 Chapter 9: Local Area Networks 12

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15. 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 Chapter 9: Local Area Networks 15

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17. 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 Chapter 9: Local Area Networks 17

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19. 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 Chapter 9: Local Area Networks 19

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21. 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. Chapter 9: Local Area Networks 21

22. 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 Chapter 9: Local Area Networks 22

23. Protocols • Token Passing • Token Bus Network • Token is taken off the network • Designed like a ring • ARCnet uses it (2.5 or 20 Mbps) Chapter 9: Local Area Networks 23

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27. Protocols • Apple Networks • Appletalk Network • Original Macintosh network • CSMA/CA • 230,400 bps, up to 32 users Chapter 9: Local Area Networks 27

28. 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 Chapter 9: Local Area Networks 28

29. Types of Networks • Private Branch Exchange LANs • Central switch in telephone system • Failure of central node is greatest threat Chapter 9: Local Area Networks 29

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31. 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 Chapter 9: Local Area Networks 31

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33. 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 Chapter 9: Local Area Networks 33

34. 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 Chapter 9: Local Area Networks 34

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36. Types of Networks • Wireless LANs • Rapidly growing technology • IEEE 802.11a, b, g standards • Cellular Digital Packet Data (CDPD) • Cellular radio technology Chapter 9: Local Area Networks 36

37. 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 Chapter 9: Local Area Networks 37

38. 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) Chapter 9: Local Area Networks 38

39. 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 Chapter 9: Local Area Networks 39

40. LAN Software • Linux • Similar to UNIX • Open source code • Alternative to high-end NOSs Chapter 9: Local Area Networks 40

41. 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 Chapter 9: Local Area Networks 41

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43. 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 Chapter 9: Local Area Networks 43

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45. 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 Chapter 9: Local Area Networks 45

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47. 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 Chapter 9: Local Area Networks 47

48. 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 Chapter 9: Local Area Networks 48

49. 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 Chapter 9: Local Area Networks 49

50. Chapter 9 Complete