Wide Area Networks (WANs)

Wide Area Networks Chapter 10Panko and PankoBusiness Data Networks and Security, 9th Edition 2013 PearsonRevised August 2013Basic ConceptsChapters 1-4Local Area NetworksLayers 1 and 2Switched Ethernet networks (Chapter 5)Local wireless networks (Chapters 6 and 7)TCP/IPLayers 3 and 4 (Chapters 8 and 9)Wide Area NetworksLayers 1-4 (Chapter 10)Where Weve Been2 2013 Pearson 2013 Pearson3Local Area Networks (LANs)On the customer premisesWide Area Networks (WANs)Connect sites across a region, country, the worldMetropolitan Area Networks (MANs)Connect sites in a single metropolitan area (a city and its suburbs)A type of WAN

10.1: LANs, MANs, and WANs4 2013 PearsonLANMANWANSitesWithinBetweenBetweenImplementationSelfCarrierCarrierAbility to choose technologyHighLowLowWho does the work of operating the network?SelfCarrierCarrier10.1: LANs, MANs, and WANs5 2013 PearsonLANMANWANPriceHighly related to costHighly unpre-dictableHighly unpre-dictableCost per bit transmittedLowMediumHighTherefore, typical speed100 Mbps to 1 Gbps or more10 to 100 Mbps1 to 50 Mbps10.1: LANs, MANs, and WANs6

2013 PearsonLANMANWANCan use switched technology?YesYesYesCan use routed technology?YesYesYes10.1: LANs, MANs, and WANs7 2013 PearsonTechnologyLANWANCan be a single switched or wireless network?YesYesCan be an internet?YesYes10.2: Single Networks versus Internets8 2013 Pearson

10.3: Components of a WAN9 2013 Pearson 2013 Pearson1010.4: PSTN Local Loop

11 2013 Pearson10.4: PSTN Local Loop

12 2013 Pearson10.4: PSTN Local Loop

13 2013 PearsonPurposeTechnologyConsiderationsBusiness Local Loop2-pair data-grade UTPFor leased lines up to about 2 MbpsMust be pulled to the customer premisesNot limited to 100 metersOptical fiber (carrier fiber)For leased lines more than about 2 MbpsMust be pulled to the customer premises10.5: Local Loop Technologies14

2013 PearsonPurposeTechnologyConsiderationsResidential Local Loop1-pair voice-grade UTPDesigned only for voice transmissionCan be used for digital subscriber line (DSL) serviceNot limited to 100 metersAlready installed; avoids cost of pulling mediaOptical fiber (carrier fiber)Fiber to the homeNewInstalled in entire neighborhoods to reduce cost10.5: Local Loop Technologies15 2013 PearsonPurposeTechnologyConsiderationsInternal Data Wiring4-pair UTP (Category 3-6A)For inside a siteUsually limited to 100 metersMultimode optical fiberLimited to about 300 meters10.5: Local Loop Technologies16 2013 Pearson

1710.6: Access Lines v Leased Lines 2013 PearsonCharacteristicDial-Up ConnectionsLeased LinesConnectivityAny-to-AnyPoint-to-pointConnection PeriodDuration of a callDuration of the lease (always on)PaymentBy the minute for long distance callsFlat rate plus per-use chargesCommitmentNone (except for cellular plans)Duration of the leaseData Transmission SpeedLow to moderateModerate to high1810.7: Dial-Up Lines v Leased Lines

2013 PearsonNorth American Digital HierarchyT11.544 Mbps2-Pair Data-Grade UTPFractional T1128 kbps, 256 kbps, 384 kbps, 512kbps, 768 kbps2-Pair Data-Grade UTPBonded T1s (multiple T1s acting as a single line)Small multiples of 1.544 Mbps 2-Pair Data-Grade UTP T344.736 MbpsCarrier Optical Fiber1910.8: Leased Line Speeds

2013 PearsonCEPT Hierarchy (Europe)E12.048 Mbps2-Pair Data-Grade UTPFractional E12-Pair Data-Grade UTPBonded E1Small multiples of 2.048 Mbps2-Pair Data-Grade UTPE334.368 MbpsCarrier Optical Fiber2010.8: Leased Line Speeds 2013 PearsonSONET/SDH SpeedsOC3/STM1155.52 MbpsCarrier Optical FiberOC12/STM4622.08 MbpsCarrier Optical FiberOC48/STM162,488.32 MbpsCarrier Optical FiberOC192/STM649,953.28 MbpsCarrier Optical FiberOC768/STM25639,813.12 MbpsCarrier Optical Fiber2110.8: Leased Line Speeds 2013 PearsonBelow 50 MbpsNorth American Digital HierarchicalCEPT Hierarchy in EuropeDifferent in other parts of the worldWire at low speeds, fiber at higher speedsAbove 50 MbpsSONET/SDHOptical fiber onlyHarmonized worldwide10.8: Leased Line Speeds 2013 Pearson22FeatureADSLVHDSLHSDLHSDL2SHDSLNameAsymmet-ric DSLVery-High-Bit-Rate DSLHigh-Rate Symmetric DSLHigh-Rate Symmetric DSL Version 2Super-High Rate Symmetric DSLUses existing 1-pair VG UTP?Yes*Yes*Yes*Yes*Yes*Target MarketResidencesResiden-tial multi-tenent buildingsBusinessBusinessBusiness2310.9: Digital Subscriber Lines (DSLs)

2013 Pearson* Duh. Thats the definition of DSLs.FeatureADSLVHDSLHSDLHSDL2SHDSLDown-streamInitially, 1.5Mbps; now upto 12 Mbps52 to 100 Mbps768 kbps1.544 Mbps384 kbps to 2-3MbpsUpstreamInitially, up to0.5 Mbps; nowup to 3.3 Mbps16 to 100 Mbps768 kbps1.544 Mbps384 kbps to 2-3MbpsSpeed Symmetry?NoYes or NoYesYesYesQoS SLA?NoNoYesYesYes2410.9: Digital Subscriber Lines (DSLs)

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2510.10: Asymmetric Digital Subscriber Line (DSL) Service for Residences

2013 Pearson2610.10: Asymmetric Digital Subscriber Line (DSL) Service for Residences

2013 Pearson2710.10: Asymmetric Digital Subscriber Line (DSL) Service for Residences

DSLAM = DSL Access Multiplexer 2013 PearsonCoaxial cable service was created to bring television to homes that had poor over-the- air receptionNow also offers two-way data service called cable modem servicePopular in the United StatesNot popular in most countries28Cable Modem Service 2013 PearsonTwo conductors: central wire and coaxial ring2910.12: Coaxial Cable

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3010.11: Cable Modem Service 2013 Pearson187654323110.11: Cable Modem Service

2013 PearsonIn general Cable modem service offers somewhat faster individual throughput at a somewhat higher cost.ADSL service offers somewhat slower individual throughput at a somewhat lower cost.32ADSL versus Cable Modem Service 2013 Pearson 2013 Pearson33

34 2013 Pearson10.13: Leased Line Data Network

10.14: Public Switched Data Network (PSDN)35 2013 PearsonX.251970s technologySlow and expensiveGone todayFrame RelayATMMetropolitan Area Ethernet3610.15: Switched Data Network Standards 2013 PearsonFrame RelayStarted to grow in the 1990sInexpensive and fast compared to X.25256 kbps to about 40 MbpsThis is the range of greatest corporate demand for WAN speeds3710.15: Switched Data Network Standards 2013 PearsonFrame RelayGrew rapidly in the 1990s thanks to low pricesTook market share away from leased line corporate networksCarriers have raised their prices to improve profit marginsThis has reduced growthMany companies are going back to leased lines for many links3810.15: Switched Data Network Standards 2013 PearsonATMMuch higher speeds than Frame Relay, at much higher pricesSpeeds of 1 Mbps to gigabits per secondAdoption for PSDN service has been limitedCreated to replace the core of the Public Switched Telephone NetworkWidely adopted for the Public Switched Telephone Network core3910.15: Switched Data Network Standards 2013 PearsonMetropolitan Area EthernetMetropolitan area network (MAN): city & environsSmaller distances than national or international WANs, so lower prices and higher speedsSpeeds of 1 Mbps to 100 MbpsLittle learning is needed because all firms are familiar with EthernetCarrier can provision or re-provision service speed rapidly, giving flexibilityThe only PSDN service growing rapidly4010.15: Switched Data Network Standards

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4110.16: Virtual Circuit OperationBox 2013 Pearson4210.16: Virtual Circuit OperationBox 2013 Pearson

10.16: Virtual Circuit Operation

43Box 2013 Pearson 2013 Pearson44To connect different sites within an organizationWide Area Networking 2013 Pearson45

The Internet is a Wide Area NetworkMany corporations are beginning to use the Internet for some part of their WAN traffic.In the future, the Internet is likely to carry most corporate site-to-site traffic and other WAN traffic.4610.17: Using the Internet for Wide Area Networking

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AttractionsThe price per bit transmitted is very low because of large economies of scale.All corporate sites, employees, customers, suppliers, and other business partners are connected to the Internet.IssuesThe security of traffic flowing over the InternetVariable quality of service, with no guarantees

4710.17: Using the Internet for Wide Area Networking

2013 PearsonBorder firewall at each siteVirtual private networksIPsec encryption for sensitive informationSSL/TLS for less sensitive informationAntivirus filtering48Securing the Internet 2013 Pearson

4910.18: Connecting All Corporate Sites to a Single ISPIf all sites connect to a single ISP, the ISP can provide QoS guarantees.

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5110.19: Cellular Technology

2013 Pearson5210.20: Cellsite for Mobile Telephones

CellsiteCellularAntennasPoint-to-Point MicrowaveAntenna to MTSO 2013 Pearson

5310.19: Cellular Technology

2013 PearsonChannel ReuseThe same channel can be used in multiple cells.This allows subscribers in different sites to use the same channel.Consequently, the carrier can serve multiple customers per channel.This is the reason for using cells(Having multiple access points in an 802.11 Building WLAN serves the same purpose)5410.21: Cellular Technology

2013 PearsonChannel ReuseChannel reuse in adjacent cellsThe concern is interference between cellsites and customers using the same channel in adjacent cells.Some cellular technologies allow channel reuse in adjacent cells, others do not.5510.21: Cellular Technology

2013 PearsonChannel ReuseExample without channel reuse: 500 channels, so only 500 simultaneous subscribers can be servedChannel reuse factor (varies): 20Number of simultaneous calls supported: 10,0005610.21: Cellular Technology

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10.19: Cellular Technology57 2013 PearsonHandoffRoamingMean the Same Thing?802.11From one access point to anotherFrom one access point to anotherYesCellular telephonyFrom one cellsite to another within the same carriers system in a cityFrom a system in one city to a carrier system in another cityNo5810.22: Handoff and Roaming in 802.11 and Cellular Networks

2013 PearsonCellular telephony has gone through several technological generations.Generation 1 (1G)1980sAnalog signalingData transmission difficult, limited to 10 kbps5910.23: Generations of Cellular Service 2013 PearsonGeneration 2 (2G)1990sDigital signalingData transmission easier but still limited to 10 to 20 kbpsSufficient for texting6010.23: Generations of Cellular Service 2013 PearsonGeneration 3 (3G)Around 2001Requirement to give at least 2 Mbps download speeds to stationary customersRequirement to give at least 384 kbps download speeds to moving customersThroughput far lower in practice initially, typically about 100 to 500 kbps stationary but still far higher than 2G6110.23: Generations of Cellular Service

2013 PearsonGeneration 3 (3G)Created an explosion in data use.Web surfing, streaming video, file synchronization, and so on are possible.Soon, some laptop computers used 3G service.Eventually, tablets and other devices used 3G.Cellular service was not just for phones anymore.6210.23: Generations of Cellular Service

2013 PearsonGeneration 4 (4G)Speed RequirementsDesigned to give at least 1 Gbps download speeds to stationary customersDesigned to give at least 200 Mbps download speeds to moving customersMakes wireless as good as or better than wired Internet accessSufficient for heavy Web downloadingSufficient for high-quality streaming video6310.23: Generations of Cellular Service

2013 PearsonGeneration 4 (4G)Technical CharacteristicsUses IP, typically IPv6MIMOScalable channel bandwidth 5 to 20 MHzFrom high but economical speeds to ultrahigh speedsStrong quality of service management6410.23: Generations of Cellular Service

2013 Pearson3G systems improved beyond the initial requirements.2013: two 3G services are dominantHSPA+ (High-Speed Packet Access)42 Mbps rated speed in the best systemsHalf that in mostActual typical speed is 7 Mbps down, 1 Mbps upLTE (Long-Term Evolution)Actual typical speed: 10 Mbps down, 6 Mbps up65Today: Closing the Gap 2013 PearsonLTE AdvancedWill be a full 4G serviceLikely to dominate 4G eventuallyLTEInternational Telecommunications Union 2010Said that precursors of 4G may be called 4GThis applied to LTEHSPA+Not a precursor to a 4G system, so not a 4G service66Which Services are 4G?

2013 PearsonCompetitor for LTEHighly comparable to LTENot thriving in the marketplaceProbably a dead-end or niche technology

67WiMAX 2013 PearsonCustomer Throughput Varies with Many FactorsSpecific technology used (e.g., LTE)Specific options used for the technology (very large effect)Channel bandwidthMIMO or not6810.24: Lies, Damned Lies, and Service Speeds

2013 PearsonCustomer Throughput Varies with Many FactorsTime of DayDuring the day, there are variationsMore traffic in the day, so slower6910.24: Lies, Damned Lies, and Service Speeds

2013 PearsonCustomer Throughput Varies with Many FactorsCustomer LocationCustomer is near center or edge of cell (distance hurts)Building or terrain obstructionsIn some locations, there may betoo few cellsites7010.24: Lies, Damned Lies, and Service Speeds

2013 PearsonCustomer Throughput Varies with Many FactorsNumber of customers sharing the cell at the momentSpeed decreases approximately linearly with the number of customersWhether the carrier minimizes this by having more cells in an area (more expensive for the carrier)7110.24: Lies, Damned Lies, and Service Speeds

2013 PearsonCustomer Throughput Varies with Many FactorsSmartphone technology and engineeringMost older smartphones cannot handle the latest carrier offerings at full speedThey will communicate using a slower older standard

7210.24: Lies, Damned Lies, and Service Speeds

2013 PearsonTraditional Roles802.11 devices received service within a building.Mobile phones received cellular service outside.7310.25: Cellular-802.11 Convergence

802.11Cellular 2013 PearsonDual Mode SmartphonesBy default, use cellular network for calls and data.But can use Wi-Fi if connected.Customers like this because it gives faster speeds than cellular transmission.Customers like this because it helps them stay under their transmission quota limits.Cellular companies like offloading air traffic from flat-fee users.7410.25: Cellular-802.11 Convergence

2013 PearsonMany Smartphones Can Act as Access PointsProvide Wi-Fi service to multiple 802.11 devices.Carriers charge a premium for this because it increases traffic and so adds to their cost.7510.25: Cellular-802.11 Convergence

CellularCarrierISP802.11

2013 Pearson 2013 Pearson76Most companies have multiple WAN technology componentsLeased line networksPSDNs of different typesInternet transmissionCellular transmissionDifferent access link technologies

7710.26: Virtual WANs 2013 PearsonTraditionally, each component has been managed separately.However, traffic between hosts often passes through multiple components.This makes it difficult to manage overall performance and efficiency.7810.26: Virtual WANs 2013 PearsonVirtual WAN software provides overall management of the individual WAN components.10.26: Virtual WANs

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79Virtual WAN software provides overall management of the individual WAN components.Allows the overall management of performance and efficiency.Individual components can be added, dropped, or changed easily as technology changes.It may be possible to simulate the effects of changes before implementation.

8010.26: Virtual WANs

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