Digital Subscriber Line (DSL)

Mary L. Pretz-Lawson

Assistant Director, Computing Services

Carnegie Mellon University

5000 Forbes Avenue

Pittsburgh, PA 15213

412-268-2642

mlpl@cmu.edu

www.cmu.edu/computing/dsl

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Carnegie Mellon Statistics

• 4,500 undergrads• 2,500 grad students• 900 FT faculty• 2,000 FT staff• 66 buildings on 100

acres

• Excels in engineering, computer science, drama, business

• 85%+ of students regularly use computers

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Computing & Communications

• 8,400 telephone lines with Verizon (Bell Atlantic) Centrex on Nortel DMS switch

• 75% IBM Type; 25% Cat 5 cabling• 70% of traffic is IP; 30% is IPX and AppleTalk• Cisco 7500s in bridged network moving to routed

network (70% complete)• Installing Gigabit Ethernet backbone using Cisco

6509s with redundant core (70% complete)

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Internet Connectivity

• Commodity connection– ATM OC3 link via Pittsburgh Supercomputing

Center– 45 Mbps total to ATT, SurfNet, Sprint, UUNet

• vBNS connection– OC3 link via School of Comp Science

• Abilene connection– OC3 link to be upgraded to OC12 link

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Carnegie Mellon Remote Access

• 300+ v.90 digital modem pool

• Early DSL trials starting in 1996

• Production DSL service in April 1999

• 600+ DSL users today, 575 with Verizon, 25 with North Pittsburgh

• CMU is ISP with ATM (Verizon) or frame (NPTC) connection to carrier

6Mary L. Pretz-Lawson, Carnegie Mellon

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ADSL - Splitting the Bandwidth

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Carnegie Mellon as DSL ISP

• Issue CMU IP addresses

• Network throughput 6 times faster on CMU DSL vs Verizon DSL

• Configure PVCs and router in compliance with Verizon’s network (ARG!)

• Computing Services Help Center takes trouble calls

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DSL Monthly Price Ranges in Western Pennsylvania

• ADSL (incl ISP)– -640K x 90K @$40-50

– 1.6M x 90K @$90-100

– 7.1M x 680K @$175-190

• Install $0-99• Modem $0-250

• SDSL (incl ISP)– 128K @$55-100

– 384K @$75-150

– 768K @$100-175

– 1.544M @$200-400

• Install $200-400 including modem

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State of DSL in Western PA

• Coverage– varies by provider– know your key areas (Squirrel Hill)

• Pricing = lower costs in future? YES!– Increased competition and lower cost cable

modems– FCC ruling on requiring RBOCs to line share

with DSL providers

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…State of DSL in Western PA

• Target Markets– is provider focusing on consumer or business

applications?– Internet surfing vs telecommuting vs research

vs remote office requirements

• Market Share– usually translates to broadest coverage– doesn’t always translate to best service/support

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…State of DSL in Western PA

• Ordering/Support– some providers still using phone/FAX ordering– most moving to online, web-based ordering and

trouble tickets

• Service Level Agreements– rarely available but important service issue– support infrastructures not yet well developed– key area for differentiation between providers

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Digital Subscriber Line Futures

• Verizon has turned up residential service in most COs

• Facility-based providers and resellers offering alternate DSL services

• Competitive DSL providers & ILECs forging liaisons (Verizon and Northpoint)

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...Digital Subscriber Line Futures

• Standards still evolving (CAP vs DMT modulation scheme)

• Splitterless technology with user-installed line filters

• DSL over fiber facilities; lower speed DSL-Lite for longer distances

• Business-grade SDSL with service level agreements

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Carnegie Mellon DSL Futures

• New part time DSL Technical Assistant

• Outsourcing ISP functions

• Local peering with ISPs to minimize hops

• VPN to provide CMU IP addresses

• ISP takes trouble calls

• Conversion to new service model in summer 2001

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Other Broadband Offerings

• Wireless local loop access alternatives• Cable modems race with DSL for market share

– some areas need cable plant upgrades

• Satellite-based DSL services appearing• Fiber to the home coming soon?• CLECs pursuing Voice over DSL to

small/medium businesses– 16 voice lines + high speed data = 1 copper pair