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

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 Networks2

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 Networks3

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 Networks4

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 Networks5

LAN Hardware Three main components –Personal computer –Network interface card (NIC) –Transmission medium Chapter 9: Local Area Networks6

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 Networks7

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 Networks8

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LAN Hardware LAN Standards –Institute of Electrical and Electronics Engineers (IEEE) IEEE 802.x standard Chapter 9: Local Area Networks10

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 Networks11

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 Networks12

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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 Chapter 9: Local Area Networks15

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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 Chapter 9: Local Area Networks17

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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 Chapter 9: Local Area Networks19

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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. Chapter 9: Local Area Networks21

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 Networks22

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 Networks23

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Protocols Apple Networks –Appletalk Network Original Macintosh network CSMA/CA 230,400 bps, up to 32 users Chapter 9: Local Area Networks27

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 Networks28

Types of Networks Private Branch Exchange LANs –Central switch in telephone system –Failure of central node is greatest threat Chapter 9: Local Area Networks29

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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 Chapter 9: Local Area Networks31

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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 Chapter 9: Local Area Networks33

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 Networks34

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Types of Networks Wireless LANs –Rapidly growing technology –IEEE a, b, g standards –Cellular Digital Packet Data (CDPD) Cellular radio technology Chapter 9: Local Area Networks36

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 Networks37

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 Networks38

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 Networks39

LAN Software Linux –Similar to UNIX –Open source code –Alternative to high-end NOSs Chapter 9: Local Area Networks40

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 Networks41

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Connecting Networks Repeaters –Cable length without repeaters limited to 1,641 feet by IEEE standard –LAN can be extended by four segments using repeaters Chapter 9: Local Area Networks43

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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 Chapter 9: Local Area Networks45

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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 Chapter 9: Local Area Networks47

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 Networks48

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 Networks49

Chapter 9 Complete