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1Practical Wireless IP: Concepts, Administration, and SecurityBrad C. Johnson &Philip CoxSystemExperts CorporationV 2.10 Copyright SystemExperts 2001,2002,20032Just checking...n This is a top level bulletn This is the next level inn this would be level 3n this would be level 4n Can you hear? Check 1…2…3…Checkn Is it too hot?Too cold?2V 2.10 Copyright SystemExperts 2001,2002,20033Jump Start Skinnyn Wireless LANs are in a state of fluxn Speed: 802.11a, 802.11b, 802.11gn Security: 802.1X, ESN, EAP, LEAPn Handhelds are in a state of consolidation and globalizationn Phones, pagers, beepers, handheld are all melding into a single devicen Permutations of protocols, capabilities, and features can be overwhelmingn Turn any card and system into an Access Pointn Use a Pringles as an antennan Expand your network without any help or noticeV 2.10 Copyright SystemExperts 2001,2002,20034Jump Start Helpn Focus on long term goalsn New applications deployed quickly -> Interoperability => Stay away from vendor specific solutionsn Reduced deployment costs -> Management Costs=> Updated policiesn Flexible infrastructure -> Network Design => Antenna homeworkn Enable business opportunities -> Architecture => Securityn Think about your real speed needsn 1 Mbps is about the same as T1n It’s hard to predict interference without tryingn Consistency (polling) vs. bandwidth (RTS/CTS)n Published speeds are not realistically possible (85% at best)3V 2.10 Copyright SystemExperts 2001,2002,20035Speed vs. InteroperabilityOFDM, CCK- OFDM54OFDM, CCK- OFDM48OFDM, CCK- OFDM36PBCC33CCK- OFDMOFDM24PBCC22OFDM, CCK- OFDM18CCK- OFDMOFDM12PBCCCCK11OFDM, CCK- OFDM9CCK- OFDMOFDM6PBCCCCK5.5Barker2Barker1Optional MethodRequired MethodBit Rate802.11GProposalV 2.10 Copyright SystemExperts 2001,2002,20036Course Contentsn What is isn Wireless, focused onn IP services for laptopsn and a little on handheld and cell-phone Internet accessn Wireless, for understandingn Security, configuration, and usagen What it isn’tn A Radio Frequency Primern An in-depth analysis of Cellular Wireless protocolsn An exhaustive list of wireless providers and devices4V 2.10 Copyright SystemExperts 2001,2002,20037Course Objectivesn When you leave this course, you should be able to:n Identify major protocols and standards used by, first and foremost, wireless LANs as well as PDAs and cell-phones n Identify important features and configuration options associated with Access Point and client cardsn Understand major threats to wireless IP networksV 2.10 Copyright SystemExperts 2001,2002,20038Where are We?n From 50,000’ to 5’ in about 24 slidesn Threatsn Handheld Practicalsn LAN Practicalsn *NIX and Wireless n Currentsn Antennas5V 2.10 Copyright SystemExperts 2001,2002,20039What is WirelessCoverage AreaLocalWideSpreadSpectrumWLANBroadband PCSNarrowband WLANCircuit & Packet DataNarrowband PCS10 mbps4 mbps2 mbps1 mbps128 kbps56 kbps19.6 kbps9.6 kbpsInfraredWLANData RatesSatellite“old” stable“new” & “unstable”V 2.10 Copyright SystemExperts 2001,2002,200310Wireless Component OverviewGateway802.11PDAWEBWAPAPPServerGatewayPSTNWiredNetworkThis CourseThis Course6V 2.10 Copyright SystemExperts 2001,2002,200311Wireless Devicesn Historicallyn Single function device (very small)n use a phone to talkn use a pager to get a phone call notificationn use a PDA to load appointmentsn General purpose devices (small)n desktop or laptop for “anything”n Now and moving into the futuren Simple devices becoming more flexiblen General purpose devices becoming (almost) as small/light as the single function devicesV 2.10 Copyright SystemExperts 2001,2002,200312General Purpose Wireless Environmentsn HomeRFn 2.4 GHz band n 1.6 Mbps from a distance of about 150 feetn Residential marketn Bluetoothn 2.4 GHz bandn Creates Personal Area Networks (PANs)n Up to 780 Kbps within a 10-meter rangen “Appliance” market7V 2.10 Copyright SystemExperts 2001,2002,200313802.11bn Unlicensed 2.4 GHz band n Uses direct-sequence spread-spectrum (DSSS)n Frequency-Hopping FHSS can only be used for 1 & 2 Mbps in US because of FCC regulationsn 1 - 11 Mbps from a distance of about 150 to 2000 feet (without special antenna)n …more on this latern Home business and business marketsV 2.10 Copyright SystemExperts 2001,2002,200314802.11 Plain and SimpleApplicationPresentationSessionTransportNetworkNetworkOperatingSystem (NOS)IPTCPData LinkPhysical802.11FH, DS, IR, CCK(b), OFDM(a)Logical Link Control (LLC) – 802.2Media Access Control (MAC) – Power Security, Etc.8V 2.10 Copyright SystemExperts 2001,2002,200315802.11bn Physical Layern Physical Medium Dependent (PMD) –wireless encodingn Physical Layer Convergence Protocol (PLCP) – common interfacen long preamble for all 802.11b systemsn short preamble for special case: e.g., streaming video, Voice-over IPn MAC Layern Inter Frame Space (IFS)n Physical Carrier Sensen Virtual Carrier Sensen e.g., hidden-noden Frame Controln Power Managementn FragmentationV 2.10 Copyright SystemExperts 2001,2002,200316802.11 A Little Less Plain & SimpleLogical Link ControlPoint Coordination Function (pcf)Distributed Coordination Function (dcf)2.2 GHzFHSS2.4 GHzDSSSInfrared 2.4GHzDSSS5.5 and 11 Mbps5GHzOFDM6,9,12,18,24,36,48,54 MbpsMACPHYData Rates1Mbps and 2 MbpsIEEE 802.11802.11b802.11a9V 2.10 Copyright SystemExperts 2001,2002,200317802.11b Frame Controln 3 types of 802.11b packetsn Management (type 00)n {association, re-association, probe} {request, response}n authentication, de-authentication, & disassociationn beaconn e.g., time-stamp, traffic indication map, supported ratesn ATIM – Announcement Traffic Information Messagen sent after each framen Control (01)n RTS, CTS, ACK, CF*, PS-Polln Data (10)n ok, data! plusn CF-ACK/Poll, etc.V 2.10 Copyright SystemExperts 2001,2002,200318802.11b IBSSn Independent Basic Service Set (IBSS)n Ad-Hoc moden Often called peer-to-peern No Access Point (AP)n i.e., with just your client cardsn No wired connections, only link wireless clients10V 2.10 Copyright SystemExperts 2001,2002,200319802.11b BSSn Basic Service Set (BSS)n Infrastructure moden Uses an AP to connect clients to a wired networkWired LANAccess PointV 2.10 Copyright SystemExperts 2001,2002,200320802.11b ESSn Extended Service Set (ESS)n Infrastructure moden Uses multiple APsn Clients may roam between APsn …more on roaming laterWired LANAccess Points11V 2.10 Copyright SystemExperts 2001,2002,200321802.11b ESSn Extension Pointn
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