-Cisco - Introduction to xDSL Technology 203-Cisco Systems (1998).pdf

Copyright © 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.1085_06F9_c1.scr 1

12031085_06F9_c1 © 1999, Cisco Systems, Inc. 12031085_06F9_c1 © 1999, Cisco Systems, Inc.

2© 1999, Cisco Systems, Inc. 2031085_06F9_c1

Introduction to xDSLIntroduction to xDSLTechnologyTechnology

Session 203Session 203


32031085_06F9_c1 © 1999, Cisco Systems, Inc.

Introduction to DSL TechnologyDigital Subscriber Line (DSL) technology unlocks the potential ofconventional copper pair telephone wire to deliver high-data-rate("broadband") digital services. Learn how this technology "turbocharges" the telephone wires available at virtually every businessand residence, and how this technology will effect you as aservice provider, enterprise customer, and everyday consumer.DSL is one of the leading technologies for bringing "megabits tothe masses" in the new emerging age of ubiquitous broadbandaccess. This session includes introduction to the family of DSLtechnologies ("xDSL"); describes how this technology enablesdelivery of high-speed data, voice and multimedia overconventional telephone wires; overview of the equipment requiredto build a DSL network on top of existing telephony infrastructure;description of value-added services enabled by "mass-market"broadband access.

AbstractAbstract

“

”


AgendaAgenda

• What Is “Broadband”?• Why Is It Important?• What Is DSL?• DSL Technology Overview• Basic DSL Network Design• New World Services• Market Dynamics



56K Is Too Slow to Provide a SatisfactoryConsumer Internet Experience

Life Beyond 56KLife Beyond 56K

• Our century-old telephone network is designed specificallyaround the audible frequency range 0-4 kHz

• Voice-band modems use tones in the audible spectrumand communicate via standard voice circuits (You canhear modems and fax machines “talking” to one another)

• 56 kbps (“56K”) is the practical limit for voice-band modems

• DSL uses inaudible high-frequency signaling to achievemegabit-transmission speeds


10x 20x 30x 40x 50x 60x 70x 80x 90x 100x

“Broadband” = “Megabit” Data Rates

56K

4Mb70x

2Mb36x

T-127x

1Mb18x

384K7x

What is “Broadband”?What is “Broadband”?

• Common unit of measure: “T-1” = 1.544 Mbps• “Fractional” T-1s, starting around 384 kbps• Compare to current maximum voice-band

modem speed of 56 kbps (“56K”)…



Broadband Access TechnologiesBroadband Access Technologies

• DSL (copper)

• Cable (coax)

• Wireless

• Optical Fiber


Consumer Access OptionsConsumer Access Options

Analog

ISDN

ADSL

CableModem

Satellite

LMDS(FixedWireless)

Requirementsand Limitations

Slow, ButAvailable

Everywhere

Reach ExtendsSeveral Miles

with Repeaters

<18K ft. fromCO, No DLC

Requires CableTV Availability;Speed Varies

Noticeably withSubscriber Load

Requires “Dish”Antenna andPhone Line

RequiresAntenna

InstallationCost

$0 (WithExisting

Phone Line)

Up to$300

Up to$500

Up to$175

Up to$800

Negotiated,Dependson Serv.Package

MonthlyExpense

Cost of PhoneLine + $19

for ISP

$19-$39 +$19-$39for ISP

$39 (Min), MayInclude Internet

Connection

$29-$49 (Min),Include Internet

Connection;May Include

Equip. Rental

Cost of PhoneLine + $29-$129,Include Internet

Connection

Varies Widely,Dependson Serv.Package

TransmissionMedium

Coax

Wireless

Copper(Std. Phone

Wire)

Copper(Std. Phone

Wire)

Copper(Std. Phone

Wire)

WirelessReq.'s

(Phone LineReturn Path)

DownloadSpeed

56 Kbps(Typically

less)

64 Kbpsor

128 Kbps

400 Kbps

384 Kbpsto

4 Mbps

144 Kbpsto

8 Mbps

1.5 Mbpsto

4 Mbps

UploadSpeed

33.6 Kbps(Or Less)

33.6 Kbps(Via 56KAnalogModem)

64 Kbpsor

128 Kbps

144 Kbpsto

1.7 Mbps

128 Kbpsto

4 Mbps

1.5 Mbpsto

4 Mbps

TargetMarket

Residential

Residentialand

Business

Residential

Residential

Business

Residentialand

Business

EquipmentCost

$0 (TypicallyIncludedwith PC)

$75 TerminalAdapter to

$500 Router

$200 PC NIC,$500 SOHO

Router(Unless Rented)

Up to $349 forSet-Top Modem,Unless Rented,Plus $29 (Min)

for Ethernet NIC

$199 (Min.)

Negotiated,Dependson Serv.Package



Deregulation and Access to “Dry Copper” HasCreated a Market for CLECs and IXCs to Provide

Lower-cost DSL Access As an Alternative toReselling Traditional Local Loops

ServiceServiceLeased Line T-1 (1.5 Mbps)Leased Line T-1 (1.5 Mbps)

Frame Relay (384 kbps)Frame Relay (384 kbps)

Business ISDN (128 kbps)Business ISDN (128 kbps)

DSL (1.5 Mbps)DSL (1.5 Mbps)

DSL (384 kbps) DSL (384 kbps)

InstallationInstallation$750-$1,500$750-$1,500

$700-$1,200$700-$1,200

$100-$350$100-$350

$400-$1,000$400-$1,000

$100-$350$100-$350

MonthlyMonthly$1,200-$1,600$1,200-$1,600

$550-$850$550-$850

$100-$250$100-$250

$900$900

$100-$150$100-$150

Business Access OptionsBusiness Access Options


RBB Enables the Full CommercialPotential of the Internet

Why is ResidentialWhy is ResidentialBroadband Important?Broadband Important?

• Fast downloads of“rich” content

Graphics, animation, audio,and video

• Always onConstant interaction with amultitude of network-aware“Internet appliances”

• Real-time, person-to-person interaction

Video conferencing, interactivegaming, multimedia collaboration

• Integrated servicesData,Voice, and Video

• New ServicesVariable bandwidth, additionallines on-demand, multimediaconferencing

• Relieves voicenetworks overloadedwith Internet traffic

Average voice call lasts threeminutes, compared to 30-60minutes per internet session



POTS

POTS

SDSLSDSL

ADSLADSL

1 MHz4 kHz0

What Is “DSL”?What Is “DSL”?

• A family of access technologies thatutilize high-transmission frequencies(up to 1 MHz) to convert ordinary phonelines into high-speed data conduits


DSL“Modem”

Value-AddedPacket

Network

End-User

DSL“Modem”

DSL

Copper LoopEnet ATM

DSL 101DSL 101

• DSL is a pair of “modems” on either end of a copper wire pair

• DSL converts ordinary phone lines into high-speed data conduits

• Like dial, cable, wireless, and T1, DSL by itself is a transmissiontechnology, not a complete end-to-end solution

• End-users don’t “buy” DSL, they “buy” services, such ashigh-speed Internet access, intranet, leased line, voice, VPN,and video on demand



DSL Modem TechnologyDSL Modem TechnologyDSL Modem Technology

• Trade-off is reach vs. bandwidth• Reach numbers are best-case assuming “clean copper”• Different Layer 1 transmission technologies, need a

common upper protocol layer to tie them together

DSL TechnologyDSL Technology Max. Data RateDown/Uplink (bps)

Max. Data RateDown/Uplink (bps)

Line CodingTechnologyLine CodingTechnology

BasebandVoice?

BasebandVoice?

VDSL –Very-High-Bit-Rate DSLVDSL –Very-High-Bit-Rate DSL

51-55M/1.6-2.3M13M/1.6-2.3M

51-55M/1.6-2.3M13M/1.6-2.3M TBDTBD YesYes

ADSL –Asymmetric DSLADSL –Asymmetric DSL

8M/1M1.5M/640K

8M/1M1.5M/640K

CAP, DMT,G.lite

CAP, DMT,G.lite YesYes

IDSL –ISDN DSLIDSL –ISDN DSL 144K/144K144K/144K 2B1Q2B1Q NoNo

SDSL –Symmetric DSLSDSL –Symmetric DSL

768K/768K768K/768K 2B1Q/CAP2B1Q/CAP NoNo

HDSL2 –High-Bit-Rate DSLHDSL2 –High-Bit-Rate DSL

1.5M-2M/1.5M-2M(T1-E1 Symmetric)1.5M-2M/1.5M-2M(T1-E1 Symmetric)

OPTISOPTIS NoNo

Max. ReachFeet (km)

Max. ReachFeet (km)

1,000 (0.3)4,500 (1.5)1,000 (0.3)4,500 (1.5)

18,000 (5.5)18,000 (5.5)

18,000 (5.5)+(w/repeaters)18,000 (5.5)+(w/repeaters)

22,000 (6.9)22,000 (6.9)

15,000 (4.6)15,000 (4.6)

Key AttributesKey Attributes

Very Fast—Short ReachNo Standard Yet

Very Fast—Short ReachNo Standard Yet

Coexists with POTSTechnology of Choice for

Residential

Coexists with POTSTechnology of Choice for

Residential

Uses Existing ISDN CPERelatively Slow

Uses Existing ISDN CPERelatively Slow

SymmetricNo standardSymmetric

No standard

Standard Still underDevelopment

Standard Still underDevelopment


ADSL “Consumer DSL”ADSL “Consumer DSL”

• Designed to co-exist with POTS, unlike mostother DSL types

• “Slow” upstream for low-data-rate requests

• “Fast” downstream for bursts of rich graphicsand multimedia content

• Three basic “flavors” of ADSL(modulation techniques)

CAP (Carrierless Amplitude modulation/Phase modulation)

DMT (Discrete MultiTone modulation)

G.lite (Consumer/mass-market DMT)



ADSL and POTSADSL and POTS

A Key Feature of ADSL Is Co-Existence with POTS

Customer Premise Central Office

DSLAMPOTSSplitter

Microfilter

POTS + ADSL ADSLADSL CPEPC

StandardAnalog Phone

DLC Class 5 Switch

AnalogVoice

NID

• Permits transmission of both signals on the same wire pair• Off-loads data circuit from the voice switch• “POTS Splitter” at the CO separates analog POTS from data• “Microfilters” at the customer premise prevent off-hook

interference between analog voice signal and ADSL signal


G.liteG.lite“Mass-Market DSL”“Mass-Market DSL”

• Simplified DMT encoding scheme

• Limited “features” to facilitate broadinteroperability and minimizeend-user interaction

• No embedded management channel

• “Splitterless”

• Max. downstream data rate = 1.5 Mbps

• Max. upstream data rate = 640 kbps



ADSL StandardsADSL Standards

• Full-rate DMTANSI T1.413—Issue 2

ITU G.992.1 (G.dmt)

ITU G.994.1 (G.hs)

• Consumer DMTITU G.992.2 (G.lite)


InteroperabilityInteroperability

Why it’s good…• Enables competition and lower

equipment costs for serviceproviders and end-users

• Lower component costs forequipment manufacturers

• Proliferation of CPE optionsfor end-users

• Retail availability of CPE(consumer mass market)

Why it’s difficult…• Standard must specify

physical layer (at all datarates) and framing

• Value-added services requireLayer 2/3 implementations

• Standards developmenttakes time



End-To-EndEnd-To-EndDSL Protocol StackDSL Protocol Stack

ATMBackbone

CPE AggregatorDSLAM Content Server

Layer 1Layer 1

Layer 2Layer 2

Layer 3Layer 3

ApplicationApplication

ATM

DSL

AAL5

PPP

IP

ApplicationProtocols

AAL5

PPP

ATM

IP

ApplicationProtocols

End-UserEnd-UserTelco

NetworkTelco

Network ISPISPContentProviderContentProvider


The Epic Battle: DSL vs. CableThe Epic Battle: DSL vs. Cable

April 20, 1999

The Faster WebDSL, Cable, and Satellite

Editors’ Choice:Cable Modems

• Performance and new-world servicesdepend more on the network designthan the transmission technology

• Cable companies have an early lead

• The Telcos have awakened

Monday, May 24, 1999

DSL Beats Cable in Net SpeedServices Tested During ‘Rush Hour’



DSL vs. Cable Bake-OffDSL vs. Cable Bake-Off

DSLDSL CableCable

Dedicated Vs. SharedDedicated Vs. Shared

DSL Is a Dedicated Connection:DSL Is a Dedicated Connection:• No bandwidth contention• Secure• No bandwidth contention• Secure

Cable Is a Shared Wire:Cable Is a Shared Wire:• Noticeable speed impairment

during “rush hour”• Near-term security issues

• Noticeable speed impairmentduring “rush hour”

• Near-term security issues

AvailabilityAvailability Telephone Wires Are UniversallyAvailable to Nearly Every Businessand Residence

Telephone Wires Are UniversallyAvailable to Nearly Every Businessand Residence

Existing Cable Is Almost ExclusivelyResidentialExisting Cable Is Almost ExclusivelyResidential

AccessibilityAccessibility Approx. 15% of Current CustomersAre Inaccessible (Out-of-reach,Bad Copper, Etc.)

Approx. 15% of Current CustomersAre Inaccessible (Out-of-reach,Bad Copper, Etc.)

Cable Head-end Equipment Must BeUpgraded or Replaced for Two-wayCommunication

Cable Head-end Equipment Must BeUpgraded or Replaced for Two-wayCommunication

ImpairmentSusceptibilityImpairmentSusceptibility

Cable Is Shielded—Signal Impairment Is Not a ProblemCable Is Shielded—Signal Impairment Is Not a Problem

CustomerSupportCustomerSupport

Established Customer SupportModels and Systems for DataServices and Per Subscriber Outages

Established Customer SupportModels and Systems for DataServices and Per Subscriber Outages

Data Service Is New and OperationsModel Is Broadcast OrientedData Service Is New and OperationsModel Is Broadcast Oriented

ConsumerAwarenessConsumerAwareness

Telcos Are the Incumbent for Voiceand DataTelcos Are the Incumbent for Voiceand Data

Cable Companies Are MovingAggressivelyCable Companies Are MovingAggressively

Telephone Wires Are Susceptible toHigh-frequency Cross-talk andExternal Impairment

Telephone Wires Are Susceptible toHigh-frequency Cross-talk andExternal Impairment


Basic DSL Network ComponentsBasic DSL Network Components

DSL CPECustomer Premise EquipmentPC NICs, bridge/routers, enterprise routers

DSLAMDSL Access Multiplexer

Concentrates individual subscriber lines from CPE

Aggregator/service selection gatewayConcentrates ATM feeds (T-1, DS-3, OC-3) from DSLAMs

PPP termination, Layer 2 and 3 service selection

On-demand, personalized services

Accounting and billing



Basic DSL Network TopologyBasic DSL Network Topology

Cisco2600/3600

Home Office,Telecommuter

Power Branch

Small-MediumEnterprise

Cisco 6400

ServiceSelectionGateway

PSTN

VVoiceGatewayCiscoAS5300

NetworkManagementandProvisioning

PacketBackbone

ATMBackbone

Residential

Cisco600

Cisco600/700/800/1000

LEC ISP

Enterprise

Home GatewayCisco 3600,6400, 7200

Internet

Home GatewayCisco 6400,

7200

• Local VoiceServices

• ManagedVoice andData VPNs

• AdditionalLinesOn-demand

• Private LineReplacement

• VideoConferencing

• Video onDemand

• High-speedInternetAccess

Mor

e B

andw

idth

= M

ore

Ser

vice

s =

Mor

e P

rofit

Opp

ortu

nitie

sM

ore

Ban

dwid

th =

Mor

e S

ervi

ces

= M

ore

Pro

fit O

ppor

tuni

ties

Cisco90iCisco90i

Cisco6100/6200Cisco6100/6200

Cisco1400/1700

Cisco 6400AggregatorCisco 6400Aggregator


COCO

SuburbsSuburbs

CityCity

RTRT

Telephone CompanyTelephone CompanyDeployment OptionsDeployment Options

• Central officeLocate DSLAM in central offices(COs) for best coverage in cities,dense suburbs

• Remote terminalLocate DSLAM in unmanned remoteterminals (RTs) for expanded coveragein suburbs and rural areas—verycommon in new developments

• CollocationIn some countries, competitive carrierscan obtain CO space from incumbentcarriers and lease “dry” copper loopsto reach customers Suburbs,Suburbs,

RuralRural



• DSL can be effective whereverthere is existing copper

• In-building networksLocated in the basement ortelco closet of hotels, apartmentbuildings, or office buildings

• Campus-style networksLocated centrally to servemulti-building campusnetworks, such as officeparks and apartment complexes

Private CopperPrivate CopperDeployment OptionsDeployment Options


Voice overData

VideoConferencing

DistanceLearning

SecureVPN

InternetAccess

E Commerce

Today BusinessConsumer

New World ServicesNew World Services



Price…and an Alternative to

Traditional AccessLoops for Lower Cost

Price…and an Alternative to

Traditional AccessLoops for Lower Cost

DSLAccessDSLAccess

ISPand/or

Enterprise

Dialup

PerformanceAlternative to PSTN/ISDN:High-Speed, Always-On

Network Access…

PerformanceAlternative to PSTN/ISDN:High-Speed, Always-On

Network Access…PSTNISDN

T1, DDS,nxDS0

Telecommuter

Residential

BranchEnterprise

Small-to-Medium-sized

Enterprise

Exploding DSL MarketplaceExploding DSL Marketplace


Market DynamicsMarket Dynamics

Attack• CLECs are pursuing small

businesses that have hadonly limited data accessoptions

• T-1 service has been tooexpensive and an overkill

• ISDN is too slow

Attack• CLECs are pursuing small

businesses that have hadonly limited data accessoptions

• T-1 service has been tooexpensive and an overkill

• ISDN is too slow

Defend• ILECs are reacting to the

onslaught of cable modems

• Defending their residentialaccess franchise

• Off-loading internet datatraffic from the voicenetwork

Defend• ILECs are reacting to the

onslaught of cable modems

• Defending their residentialaccess franchise

• Off-loading internet datatraffic from the voicenetwork



“

”

This Changes Everything…This Changes Everything…

Broadband Internet AccessThreatens POTS

Subscriber Loyalties ThatHave Withstood Decadesof Low-price Come-ons


More, Better, Faster, CheaperMore, Better, Faster, Cheaper

• It’s no longer just about cheaper phone bills…

• Now it’s about high-speed Internet access…

• And, “Oh, by the way”, bundled voice lines…

• And, value-added voice/data/video services!

Consumer Proposition



• DSL is ready for prime time!

• Data-traffic volumes are eclipsingvoice-traffic volumes on thepublic networks

• Carriers have tested DSL,and now need to scale formass deployment

• Profits in an era oflow-cost access will comefrom new- world services

SummarySummary

Data

Voice


Please Complete YourPlease Complete YourEvaluation FormEvaluation Form

Session 203Session 203



331085_06F9_c1 © 1999, Cisco Systems, Inc. 2031085_06F9_c1

Documents

-Cisco - Introduction to xDSL Technology 203-Cisco Systems (1998).pdf