© 2009 Prentice-Hall, Inc. 11

2 Technology in Action Chapter 12 Behind the Scenes: Networking and Security

© 2009 Prentice-Hall, Inc. 3 Chapter Topics Advantages of business networksAdvantages of business networks Client/server vs. peer-to-peer networksClient/server vs. peer-to-peer networks Classifications of client/server networksClassifications of client/server networks Client/server network componentsClient/server network components Types of serversTypes of servers Network topologiesNetwork topologies

© 2009 Prentice-Hall, Inc. 4 Chapter Topics (cont.) Types of transmission mediaTypes of transmission media Network softwareNetwork software Network adaptersNetwork adapters Moving data in a client/server networkMoving data in a client/server network Securing networksSecuring networks

© 2009 Prentice-Hall, Inc. 5 Networking Advantages NetworksNetworks –Increase productivity –Enable the sharing of hardware resources –Facilitate knowledge sharing –Enable the sharing of software –Facilitate Internet connectivity –Enable enhanced communication

© 2009 Prentice-Hall, Inc. 6 Client/Server Networks Server-based networkServer-based network –Clients and servers Data flows efficientlyData flows efficiently Servers respond to requests from clientsServers respond to requests from clients Servers perform specific tasksServers perform specific tasks ScalableScalable CentralizedCentralized

© 2009 Prentice-Hall, Inc. 7 Classifications of Client/Server Networks LANLAN –Local area network –Computers linked over a small geographic region

© 2009 Prentice-Hall, Inc. 8 Classifications of Client/Server Networks WANWAN –Wide area network –Computers linked over large geographic locations MANMAN –Metropolitan area network –Computers linked within a city or county

© 2009 Prentice-Hall, Inc. 9 Classifications of Client/Server Networks PANPAN –Personal area network –Wireless devices connected in close proximity to each other IntranetIntranet –Private corporate network –Protected by a firewall

© 2009 Prentice-Hall, Inc. 10 Constructing Client/Server Networks ServersServers Network topologiesNetwork topologies Transmission mediaTransmission media Network operating system softwareNetwork operating system software Network adaptersNetwork adapters Network navigation devicesNetwork navigation devices

© 2009 Prentice-Hall, Inc. 11 Servers Number and type of servers depend on network size and workloadNumber and type of servers depend on network size and workload Dedicated serversDedicated servers –Perform one specific function Authentication serversAuthentication servers –Keep track of network logins and services available File serversFile servers –Store and manage files

© 2009 Prentice-Hall, Inc. 12 Servers Print serversPrint servers –Manage client-requested printing jobs –Create print queue (prioritize print jobs) Applications serversApplications servers –Act as a storage area for application software Database serversDatabase servers –Provide clients with access to database information servers servers –Process and deliver incoming and outgoing

© 2009 Prentice-Hall, Inc. 13 Servers Communications serversCommunications servers –Handle communications between networks including the Internet –Often the only device on the network directly connected to the Internet Web serversWeb servers –Host a Web site available through the Internet

© 2009 Prentice-Hall, Inc. 14 Network Topologies The physical layout of computers, transmission media, and other componentsThe physical layout of computers, transmission media, and other components Types of network topologiesTypes of network topologies –Bus topology –Ring topology –Star topology –Hybrid topology

© 2009 Prentice-Hall, Inc. 15 Bus Topology All nodes are connected in sequence on a single cableAll nodes are connected in sequence on a single cable Used most often on peer-to-peer networksUsed most often on peer-to-peer networks Networked computers communicate with each otherNetworked computers communicate with each other One computer transmits data at a timeOne computer transmits data at a time –Access methods avoid data collisions –Data is transmitted in “packets”

© 2009 Prentice-Hall, Inc. 16 Ring Topology Nodes are laid out in a ringNodes are laid out in a ring Token (data packet) flows in one direction from device to deviceToken (data packet) flows in one direction from device to device Recent versions have data transfer rates up to 100 MbpsRecent versions have data transfer rates up to 100 Mbps

© 2009 Prentice-Hall, Inc. 17 Star Topology Nodes connect to a central communications device (switch)Nodes connect to a central communications device (switch) A node sends a signal to the switch, which retransmits it to the other nodesA node sends a signal to the switch, which retransmits it to the other nodes A node accepts only signals addressed to itA node accepts only signals addressed to it

© 2009 Prentice-Hall, Inc. 18 Avoiding Data Collisions on an Ethernet Network

© 2009 Prentice-Hall, Inc. 19 Transmission Media The routes data takes to flow between devices on a networkThe routes data takes to flow between devices on a network WiredWired WirelessWireless

© 2009 Prentice-Hall, Inc. 20 Choosing a Cable Maximum run lengthMaximum run length BandwidthBandwidth Bend radiusBend radius Cable costCable cost Cable and installation costsCable and installation costs Susceptibility to interferenceSusceptibility to interference Signal transmission methodsSignal transmission methods

© 2009 Prentice-Hall, Inc. 21 Twisted Pair Cable Pairs of copper wire twisted around each otherPairs of copper wire twisted around each other Twists make the wires less susceptible to interferenceTwists make the wires less susceptible to interference Shielded twisted pair (STP)Shielded twisted pair (STP) –Layer of foil shielding Unshielded twisted pair (UTP)Unshielded twisted pair (UTP) –Cat 5E: Bandwidth 200 Mbps –Cat 6: Bandwidth 1 Gbps –No foil layer STP

© 2009 Prentice-Hall, Inc. 22 Coaxial Cable Four componentsFour components –Copper core –Nonconductive insulating material –Braided metal –Plastic cover

© 2009 Prentice-Hall, Inc. 23 Fiber-Optic Cable Components includeComponents include –Glass or plastic fibers –Cladding –Outer jacket Uses light impulses to transmit dataUses light impulses to transmit data Immune to interferenceImmune to interference

© 2009 Prentice-Hall, Inc. 24 Wireless Media Standard Wi-Fi, short for Wireless FidelityWi-Fi, short for Wireless Fidelity –802.11b –802.11a –802.11g –Super G –802.11n

© 2009 Prentice-Hall, Inc. 25 Network Operating Systems (NOS) Provide the protocol that controls the communication between devices on the networkProvide the protocol that controls the communication between devices on the network Many modern OSs include NOS client softwareMany modern OSs include NOS client software Major network operating systemsMajor network operating systems –Windows Server 2003 –UNIX –Novell NetWare

© 2009 Prentice-Hall, Inc. 26 Network Adapters Devices that enable computers to communicate on a networkDevices that enable computers to communicate on a network Network interface cards (NICs)Network interface cards (NICs) Three functionsThree functions –Generate network transmission signals –Create data packets –Act as information gatekeepers Ethernet compliantEthernet compliant Wireless NICsWireless NICs

© 2009 Prentice-Hall, Inc. 27 Network Navigation Devices Media Access Control (MAC) addressMedia Access Control (MAC) address –Six two-digit numbers (01:40:87:44:79:A5) –Physical address of network adapter –Internal network identification Repeaters and HubsRepeaters and Hubs –Amplify signals and retransmit them

© 2009 Prentice-Hall, Inc. 28 Network Navigation Devices Switches and BridgesSwitches and Bridges –Send data on a specific route through the network –Bridges send data between collision domains RoutersRouters –Send information between two networks

© 2009 Prentice-Hall, Inc. 29 Network Security Threats Human errors and mistakesHuman errors and mistakes –Accidents and mistakes Malicious human activityMalicious human activity –Current and former employees hacking or planting viruses Natural events and disastersNatural events and disasters –Hurricanes, floods, fire

© 2009 Prentice-Hall, Inc. 30 Network Security AuthenticationAuthentication –User ID and password used to access the network –Use of a possessed object for access Access privilegesAccess privileges –Enable access to certain network systems Physical protection measuresPhysical protection measures –Restrict physical access to sensitive network equipment –Magnetic card readers –Biometric access devices

© 2009 Prentice-Hall, Inc. 31 Network Security FirewallsFirewalls –Prevent access to the network by unauthorized users –Composed of software and/or hardware –Screen and validate data packets –Bastion host/proxy server

© 2009 Prentice-Hall, Inc. 32 Network Firewall Layout

© 2009 Prentice-Hall, Inc. 33 Chapter 12 Summary Questions What are the advantages of a business network?What are the advantages of a business network?

© 2009 Prentice-Hall, Inc. 34 Chapter 12 Summary Questions How does a client/server network differ from a peer-to-peer network?How does a client/server network differ from a peer-to-peer network?

© 2009 Prentice-Hall, Inc. 35 Chapter 12 Summary Questions What are the different classifications of client/server networks?What are the different classifications of client/server networks?

© 2009 Prentice-Hall, Inc. 36 Chapter 12 Summary Questions What components are needed to construct a client/server network?What components are needed to construct a client/server network?

© 2009 Prentice-Hall, Inc. 37 Chapter 12 Summary Questions What do the various types of servers do?What do the various types of servers do?

© 2009 Prentice-Hall, Inc. 38 Chapter 12 Summary Questions What are the various network topologies (layouts), and why is network topology important in planning a network?What are the various network topologies (layouts), and why is network topology important in planning a network?

© 2009 Prentice-Hall, Inc. 39 Chapter 12 Summary Questions What types of transmission media are used in client/server networks?What types of transmission media are used in client/server networks?

© 2009 Prentice-Hall, Inc. 40 Chapter 12 Summary Questions What software needs to be running on computers attached to a client/server network, and how does this software control network communications?What software needs to be running on computers attached to a client/server network, and how does this software control network communications?

© 2009 Prentice-Hall, Inc. 41 Chapter 12 Summary Questions How do network adapters enable computers to participate in a client/server network?How do network adapters enable computers to participate in a client/server network?

© 2009 Prentice-Hall, Inc. 42 Chapter 12 Summary Questions What devices assist in moving data around a client/server network?What devices assist in moving data around a client/server network?

© 2009 Prentice-Hall, Inc. 43 Chapter 12 Summary Questions What measures are employed to keep large networks secure?What measures are employed to keep large networks secure?