Network Architectures for a Multi-Service Broadband Internet

George Clapp973-829-4610clapp@research.telcordia.comFriday, April 21, 2023

Multi-Service Broadband Internet Architectures – 2

Growth in the Number of HostsNetSizer

40

45

50

55

60

65

70

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eb-9

9

Mar

-99

Apr

-99

May

-99

Jun-

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Jan-

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Date

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http://www.netsizer.com/daily/table.html

Multi-Service Broadband Internet Architectures – 3

Worldwide Business-to-Business E-Commerce

GartnerGroupJanuary 26, 2000http://gartner12.gartnerweb.com/public/static/aboutgg/pressrel/pr012600c.html

7% of $105T total global sales transactions

0.145 0.4030.953

2.18

3.95

7.29

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2

3

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1998 2000 2002 2004

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Multi-Service Broadband Internet Architectures – 4

Multi-Service Broadband Internet Architectures – 5

Access to the Internet

http://www.stanford.edu/dept/news/report/news/february16/internetsurvey-216.html

Stanford Institute of Quantitative Study of Society– Polled 4,113 individuals; 2,689 households

Multi-Service Broadband Internet Architectures – 6

Increasing Use with Time

http://www.stanford.edu/dept/news/report/news/february16/internetsurvey-216.html

Multi-Service Broadband Internet Architectures – 7

Generational Differences in Use of the Internet

Multi-Service Broadband Internet Architectures – 8

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

19

93

19

94

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Multi-Service Broadband Internet Architectures – 9

Market Demand for High Speed Access

Total BBD + ISDN Market

ADSL (Bellcore)

Cable Modems (Kagan)

ISDN BRI (IDC 98)

0

5

10

15

20

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1997 1998 1999 2000 2001 2002 2003 2004

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Multi-Service Broadband Internet Architectures – 10

Source: IDC/Link 9/98

ForecastsOne View

Multi-Service Broadband Internet Architectures – 11

Simplistic but true

2000

2001 2002 2003 2004 2005

Data

Voice

0

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2000 2001 2002 2003 2004 2005

Voice

Data

Traffic Growth RatesVoice grows at 3% per year; data grows at 100% per year

Multi-Service Broadband Internet Architectures – 12

Parts of a Network

Othercarriers

Premises Access Metropolitan

Operations

Backbone(long-haul)

Transmission

Switching

Multi-Service Broadband Internet Architectures – 13

Access Networks

AccessMultiplexer(s)

Wireless

Voice Switch

POTS (Plain Old Telephone Service)

Digital Subscriber Line (DSL) xDSLxDSL

Modem

Fiber in the loop (FITL)Fiber to the X (FTTx)

Optical Network Unit (ONU)

Hybrid Fiber Coax (HFC)

HUB

ONU

Multi-Service Broadband Internet Architectures – 14

Cable Networks

Headend

PrimaryHub

PrimaryHub

PrimaryHub

SecondaryHub

SecondaryHub

Node

Node

Few hundred thousand homes passed

Node

Node

Few tens of thousands homes passed

Few hundred to thousand homes passed

Info

rmatio

n

Multi-Service Broadband Internet Architectures – 15

http://www.webproforum.com/hfc_dwdm/

Cable NetworksAnother View with Neighborhoods

Multi-Service Broadband Internet Architectures – 16

PSTN Gateway

PacketCable Architecture

CableModem

MTA

CableModem

MTA

HFC access network

HFC access network

CMTS

CMTS

Call Management Server (CMS)

Announcement Server

OSSBack OfficeServers and Applications

Media Gateway (MG)

Signaling Gateway

MG Controller

PSTN

ManagedIP Network

PSTN: Public Switched Telephone NetworkCMTS: Cable Modem Termination SystemMTA: Multimedia Terminal Adapter

Multi-Service Broadband Internet Architectures – 17

Cable Distribution Network

V

CMTS

PSTN Gateway

HFC

MTA

CMTS

HFC

MTA

PSTN

Head End

Multimedia Cable Network Systems (MCNS)Data over Cable System Interface Specifications (DOCSIS)

Multi-Service Broadband Internet Architectures – 18

Cable Voice over IP Architecture

CiscoCisco

IP Network ILEC/PTOV

HFC Network

VoIP Infrastructure

VoIPTrunking Gateway

GigaBit Switch RoutersPacket Over Sonet

IntegratedCMTS/HeadEnd Router

CPECable Modem

Multi-Service Broadband Internet Architectures – 19

Cable Voice over IP Architecture cont’d

V

GSR12008GSR12008 OC-12

OC-12

VVV

Public TelephoneNetwork

Cat8500

TRUNKGATEWAYS

CMTS/HEADEND ROUTER

CAMPUSSWITCH ROUTER

BACKBONEROUTERS

AS5300

uBR7246

Cat8500

Optical Nodes

Multi-Service Broadband Internet Architectures – 20

Typical HFC Frequency Plan

750,860 MHz,1 GHz

5 MHz 42 MHz 550 MHz54 MHz

Ch 78

Upstream Downstream

2-way servicesDigital Video

AM Video2-way services

Ch2

320 Kbps to 10 Mbps

30 to 40 Mbps/6 MHz channel

Upstream and downstream data channels are shared

Multi-Service Broadband Internet Architectures – 21

DSLAM: Digital Subscriber Line Access Multiplexer

ADSL

Asymmetric Digital Subscriber Line

ATMSwitchFabric

Class 5Switch

To ISPs,IXCs

ADSL Modem

Data Rate(Mbps)

Wire Gauge(AWG)

Distance (ft)

1.5–2.0 24 18,0001.5–2.0 26 15,000

6.1 24 12,0006.1 26 9,000

Multi-Service Broadband Internet Architectures – 22

ADSL Access

http://www.3com.com/solutions/dsl/dsl_tech_microwt.html#_Toc389638794

Multi-Service Broadband Internet Architectures – 23

Differences between ADSL and HFC

ADSL is dedicated point-to-point technology

ADSL peak rate is 6 Mbps downstream; average rate is typically 1-2 Mbps

ADSL upstream rates are typically 1/10 of downstream

Cable modem is a shared bus (typically 100 customers)

Cable modem peak rate is 30-40 Mbps shared over all customers currently active

Cable modem systems typically have a single shared upstream channel at lower rate

Multi-Service Broadband Internet Architectures – 24

ADSL– Downstream: 1 Mbps to 8 Mbps

– Upstream: 128 kbps to 640 kbps

– Range: 12 kft to 18 kft

G.lite– Downstream: 1.5 Mbps

– Upstream: 512 kbps

– Range: 18 kft

VDSL– Downstream: 13 Mbps to 52 Mbps

– Upstream: 1 Mbps to 4 Mbps

– Range: 1 kft to 4 kft

– For use off of DLC RDT or FTTC ONU

IDSL– Downstream: 128 kbps

– Upstream: 128 kbps

– Range: 18 kft

– No POTS

HDSL– Downstream: 1.544/2.048 Mbps

– Upstream: 1.544/2.048 Mbps

– Range: 12 kft

– Requires Two Pair

– Used for commercial T1/E1 service

– Taking the majority (70% of U.S. in 1996) market for T1s

SDSL (One Pair HDSL)– Downstream: 784 kbps

– Upstream: 784 kbps

– Range: 12 kft

– No POTS

Types of xDSL

Multi-Service Broadband Internet Architectures – 25

Limitations and Obstacles to xDSL

Distance limited, Maximum loop length dependent on– Data rate

– Gauge makeup

Bridged Tap Load Coils Noise Crosstalk Serving Arrangement - Copper vs. DLC

Multi-Service Broadband Internet Architectures – 26

Working Length - All RBOCs

0%

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0.5 1 1.5 2 2.5 3 3.5 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18kilofeet

All

Urban

Suburban

Rural

Total Loop Length National Segmentation

41% Urban 50% Suburban 9% Rural

Multi-Service Broadband Internet Architectures – 27

Digital Loop Carrier Digital Loop Carrier (DLC) Solution Needed

– Over 20% of US loops served by DLC

– Much higher in some regions of the country

– Majority of new growth served by DLC

– Many of the affluent, suburban, prime ADSL subscriber neighborhoods served by DLC

0%

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Fiber fed DLC

Copper fed DLC

1998 DLC Deployment

Multi-Service Broadband Internet Architectures – 28

National Loop Statistics

Load Coils– Approximately 2% - 8% of all loops are loaded

– xDSL will not operate over loaded lines

Bridged Tap– Approximately 70%-80% of all loops have one or more Bridged Tap

– Bridged Tap are generally not a problem.

– Lowers SNR by a few dB resulting in small decrease in range

– Bridged-tap at or very close to the Quarter-wavelength length may cause more problems

Multi-Service Broadband Internet Architectures – 29

T1 lines and ADSL– Near End Cross Talk (NEXT) from T1 can nearly stop downstream ADSL– NEXT from ADSL can disrupt T1

Repeatered HDSL and ADSL– HDSL repeaters can destroy ADSL on long loops.

ADSL and VDSL– NEXT from ADSL can significantly hurt VDSL signals

Unbundling xDSL, and different CLECs – May cause incompatibilities between various flavors of xDSL

Spectral Compatibility

Multi-Service Broadband Internet Architectures – 30

Summary

xDSL allows LECs to deploy high speed data services quickly and economically over their existing infrastructure

At the same time, the xDSL addressable market is constrained by the existing infrastructure

Loop Qualification is a necessity DLC solutions are necessary to unlock more potential

subscribers

Multi-Service Broadband Internet Architectures – 31

Emergence of “Double-Bubble” Networks

IP Network

Gateway Gateway

PSTN

Incumbent Local Exchange Carriers (ILECs) build out a separate IP network

Multi-Service Broadband Internet Architectures – 32

Dense Wave Division Multiplexing

Multiplex wavelengths into a single optical fiber Lucent WaveStar OLS 400G supports up to 80 optical channels

of 2.5 Gb/s each over a single fiber

http://www.webproforum.com/dwdm/topic01.html

Multi-Service Broadband Internet Architectures – 33

New Options in Protocol Stacks

WDM Optical NetworkWDM Optical Network

SONET/SDHSONET/SDH SONET/SDHSONET/SDH ATMATM IPIP

IPIP

ATMATM IPIP IPIP

Physical Fiber PlantPhysical Fiber Plant

Multi-Service Broadband Internet Architectures – 34

ATMSwitch

DWDM as Capacity Expansion

SONET ADM

SONETADM

SONET ADM

SONET ADM

WDM

WDM

IP Router

IP Router

ATM uplink on OC-3c

OC-48

OC-48

ATM uplink on OC-3c

OC-48

OC-48

OC-3c

OC-3c

ADM: Add Drop Multiplexer

Multi-Service Broadband Internet Architectures – 35

Elimination of SONET

WDM

WDM

ATMSwitch

IP Router

IP Router

ATM uplink on OC-48

ATM uplink on OC-48 OC-48

OC-48

Multi-Service Broadband Internet Architectures – 36

Revisiting Cable Networks with DWDM

http://www.webproforum.com/hfc_dwdm/index.html

Multi-Service Broadband Internet Architectures – 37

NMS(s)NMS(s)

WDM

WDM

WDM

WDM

WDMEMSWDMEMS

IPRouter

IPRouter

Internet

IPRouter

IPRouter

CableAccess

Cable

Cable Modem

IPRouter

IPRouter

IPRouter

IPRouter

IPEMSIP

EMS

Backbone IP Network

Multi-Service Broadband Internet Architectures – 38

Target Internet Backbone Architecture

WDMWDM

RoutersRouters ServersServers

Multi-Service Broadband Internet Architectures – 39

The Quality of Service ChallengeTransmission of voice through data networks

Delay

Jitter

Losses

150 msec one way delay Minimum jitter buffer of 15 msec 1-2% packet loss

Multi-Service Broadband Internet Architectures – 40

The rising tide:a first answer to the quality concern

0.1

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1983 1987 1991 1995 1999 2003

Tra

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Historical modem speeds

"Moore's Law" prediction

Multi-Service Broadband Internet Architectures – 41

The delays are already almost acceptablebut there are wide variations

0%

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TCP connection delays (ms)

Multi-Service Broadband Internet Architectures – 42

Congestion happens!

•Loss of transmission resource

•Olympic games, earth-quake, TV show...

Multi-Service Broadband Internet Architectures – 43

Diffserv and Edge Control:Solving the QoS challenge

Managed IP backbone

Edge router

Customer

Multi-Service Broadband Internet Architectures – 44

Evolution of the NetworkTwo options for quality of service

1: Rising tide 2: Retooling

Diffserv

Ban

dw

idth

Multi-Service Broadband Internet Architectures – 45

Different Requirements for Voice and Data

Voice– Sensitive to delay and jitter

– Low tolerance for packet loss

Data– Delay insensitive

– Packet loss dramatically reduces throughput

Small buffers– VoIP delays lie within acceptable bounds; compliance with loss

bounds are ensured only for low loads of TCP traffic

– Severe degradation of TCP performance even at very low loads since the buffers are unable to accept even small bursts that are generated by a TCP flow

Large buffers – Good throughput for TCP

– VoIP traffic suffers a sharp increase in jitter at even moderate buffer sizes

Multi-Service Broadband Internet Architectures – 46

Separation of traffic with priority classesVoice > Data

Multi-Service Broadband Internet Architectures – 47

Conclusion

Continued exponential growth in size and functionality of the Internet

Thanks for fiber optics, network technology is keeping pace with demand