dslpresent

Slide1: 

Judith Hellerstein, President Hellerstein & Associates 2400 Virginia Avenue NW Washington, DC 20037 Phone: (202) 333-6517 Judithh@tmn.com www.jhellerstein.com XDSL ComForum, TechForum: Session TF2 TechForum, July 19, 1999 xDSL Fundamentals The ABCs of xDSL

Outline: 

Outline What is DSL What does the x in front of DSL stand for an explanation of the different DSL technologies DSL Standards Organizations xDSL Benefits How DSL Compares with Other Broadband Technologies Target Markets XDSL Deployment Hurdles DSL Providers

Overview: 

Overview What is DSL? DSL Uses DSL can be used to transmit applications between users Video conferencing and whiteboards IP Faxes Remote connections to a corporate LAN Fast Internet access Interactive multimedia

Overview (cont): 

Overview (cont) DSL Components DSLAM DSL end-user Modem USB external modem PCI Card DSL Bridge Single User vs. Multi User solutions

xDSL Flavors: 

xDSL Flavors The x in xDSL is simply a way of notating the variety of flavors of DSL. Each flavor has its own limitations, capabilities, and offers different speeds Asymmetric vs. Symmetric Asymmetric speeds are predominantly targeted to the consumer market, while symmetric is targeted to business market

xDSL Flavors (continued) : 

xDSL Flavors (continued) Eight different DSL flavors ADSL DSL-Lite UDSL RADSL SDSL IDSL HDSL/HDSL 2 VDSL

xDSL Flavors (continued): 

xDSL Flavors (continued) Each flavor is dependent on three factors: The distance between the end user and the central office. The DSL equipment used The service offering from the ILEC, CLEC, or ISP. DSL functionality is determined by the chipset that is included in the flavor offered. DSL chipsets can be upgraded if necessary software is provided

Asymmetric Digital Subscriber Line: 

Asymmetric Digital Subscriber Line Downstream speeds are significantly higher than upstream, as high as 8mb downstream and as slow as 384k upstream. Is primarily a consumer technology since it cannot provide the same bandwidth upstream and downstream Transmission speeds depend on the distance between the end-user and the central office

ADSL (Continued): 

ADSL (Continued) Preserves POTS lines by splitting off the data from the voice channel. Requires the installation of a splitter in both the users home and in the ILEC Central office Installation of a splitter requires the sending of a technician to the users home Installation costs are significantly higher Supports multiple line codes, DMT, CAP Requires the carriers to have installed an ADSL access multiplexer in the subscriber’s central office. Very susceptible to interference and crosstalk

ADSL (continued): 

ADSL (continued) Costs of architecture Customer premise equipment modifications needed to be completed at central office cost of the backbone networking to provide Internet access Where can routers and Ethernet switchboards be most efficiently and effectively deployed

ADSL (continued): 

ADSL (continued) Architecture needs more definition Problems with Spectral Compatibility occur when more than one ADSL pair is in the cable binder Interoperability issues between ADSL and other DSL technologies and DSLMs Scalability

Rate Adaptive DSL: 

Rate Adaptive DSL Allows modems to automatically adjust their transmission speeds depending on the distance and quality of the connection Opens up ADSL to a larger audience Preserves POTS lines by splitting off the data from the voice channel Requires the installation of a splitter in both the users home and in the ILEC Central office Installation of a splitter requires the sending of a technician to the users home Installation costs are significantly higher

RADSL (continued): 

RADSL (continued) Transmission speeds depend on the distance between the end-user and the central office Downstream speeds range from 64K to 7 Mbs Upstream speeds range from 64k to 1Mb Downstream and upstream channels can be split to into several sub-channels up to four sub channels downstream up to three bi-directional sub-channels Is the technology of choice and is used by most RBOCs to deploy ADSL to the consumer market

DSL-Lite: 

DSL-Lite The newest DSL standard, a product of the Universal ADSL Working Group Commercial release expected this fall ITU Certified under the name G.Lite Based on ITI G.992.1 and G.992.2 Designed for the consumer marketplace

DSL-Lite (continued): 

DSL-Lite (continued) Derived from ADSL, but operates at a lower speed and frequency Easy upgrade path to full rate ADSL Uses the DMT line code Require less power to operate Greater accessibility, able to extend to 18,000 feet from the Central Office Designed to be spectrally compatible with other high speed access technologies

DSL-Lite (continued): 

DSL-Lite (continued) Less costly to deploy than full rate ADSL Does not require splitters Eliminates the need for an installer from the phone company Consumer friendly Designed to be truly Plug-and-Play, but microfilters have been found to be necessary Significantly slower speeds than rate ADSL Downstream speeds range from 384k-1 Mb Upstream speeds from 384k-512k

DSL-Lite (continued): 

DSL-Lite (continued) Speed affected by four factors: Distance between carrier and user Allowable error rate User premise wiring User premise phone equipment

Universal DSL: 

Universal DSL Paradyne’s Multiple Virtual Lines Nortel Networks’s One Meg Modem

Paradyne: 

Paradyne A proprietary technology that allows one line to be split into eight virtual lines Requires only a single pair of twisted copper wire Splitterless Symmetric Works in many places DSL does not operate Offers speeds of up to 768K downstream

Nortel Networks: 

Nortel Networks Splitterless Downstream speeds limited to 960K and 120K upstream. Supports line lengths of up to 13,000 feet without loss in throughput

Splitter: 

Splitter A three node device that enables ADSL and other DSL technologies to separate the data channels from the POTS line. Filters and blocks noise and interference coming from the home telephone to the ADSL modem. Often needs to be installed on all telephony devices Located in the low frequency band below 4KHz

Signalling: 

Signalling A process whereby an electrical signal is transmitted over a wire for transmission High frequency signals over copper loops dissipate energy faster than lower frequency signals Modulation techniques minimizes loss of electrical energy as it passes over copper wire by reducing the frequency. Modulation is based on different line codes Some line codes are spectrally incompatible with other line codes.

Line Codes: 

Line Codes DMT CAP 2B1Q (2 binary 1 quaternary)

What is Discrete Multitone Modulation (DMT): 

What is Discrete Multitone Modulation (DMT) DMT is a form of multiplexing. Recognized as the ADSL standard by the ITU, ANSI, and ETSI. (T1.413 issue 2) Works by dividing the bandwidth into may independent sub-bands and then transmitting the data on all simultaneously Varies the traffic on each channel to overcome noise and interference in the spectrum

What is Carrierless Amplitude Phase Modulation (CAP): 

What is Carrierless Amplitude Phase Modulation (CAP) CAP is an alternative line code that has been used in many deployments of DSL, but has never been approved as a DSL standard by any of the standards bodies. Works by treating the entire frequency spectrum available as a single channel and then optimizes the data rates over the channel

ISDN DSL (IDSL): 

ISDN DSL (IDSL) IDSL is a DSL version of ISDN Easy to install and maintain Can be provisioned on any ISDN capable line Uses 2B1Q line code Offers downstream/upstream speeds of 144K Speeds not upgradeable Typically offered without a voice component, however, Ascend and other companies are now selling equipment that can deliver voice over DSL

IDSL (continued): 

IDSL (continued) Supports line lengths up to 24,000 feet from the central office Offers a longer reach than other versions of DSL Not susceptible to crosstalk, noise, and interference Digital Loop Carriers pose no barriers to IDSL Able to use ISDN repeaters to extend technology’s reach

High Data Rate DSL (HDSL): 

High Data Rate DSL (HDSL) One of the most mature of all DSL technologies Created to provide a simpler and cheaper way of provisioning T-1 or E-1 access over copper lines Today it is the most common way of provisioning T-1 Lines Not as susceptible to cross talk or other interference Able to use repeaters to extend the service and coverage area Requires the installation of two twisted pairs of copper (4 wires) Uses DMT, CAP, and 2B1Q line codes

HDSL 2: 

HDSL 2 Same as HDSL, but requires only one twisted copper pair, rather than two Use of one pair dramatically reduces the number of repeaters needed, which in turn reduces the costs Enables HDSL 2 to penetrate the small business and teleworker marketplace Offers upstream and downstream speeds of one Mb, the same as HDSL Speeds of up to 3 mbs can be obtained by using two twisted pairs over the same distance

HDSL 2 (continued): 

HDSL 2 (continued) Able to extend to 18,000 without repeaters Preserves POTS lines by splitting off the data from the voice channel Requires the installation of a splitter Appears to be impervious to crosstalk, noise, and other interference.

HDSL 2 (continued): 

HDSL 2 (continued) No apparent spectral compatibility issues with ADSL, T-1s, or ISDN Technology is based on Overlapped Pulse-Amplitude Modulation (PAM) with Interlocking Spectra (OPTIS) line code. Interoperability tests have been completed Received full ANSI approval ITU approval expected shortly

Symmetric DSL (SDSL): 

Symmetric DSL (SDSL) Offers a modified version of HDSL Uses only one twisted pair of copper wires Provides speeds up 1.5 Mb in both directions upstream and downstream Many users claim they can only receive close to 800K Limited to distances less than 8,000 feet from the central office Technology of choice for small businesses and teleworkers

Very High Speed DSL: 

Very High Speed DSL Technology of choice for transmitting movies and video entertainment over the web Downstream rates are as high as 52 Mb and upstreams as high as 3 Mb VDSL standard is a joint effort by ANSI, ETSI, DAVIC, the ADSL and ATM forums, and the IEEE. Provides the final link between the fiber network and the end user.

VDSL (continued): 

VDSL (continued) Two versions are being marketed Fiber to the node Fiber to the home Fiber needs to be installed within 3,000-4,000 of central office Spectral compatibility has not been determined Can only be used over short distances of less than one thousand feet

Single User Solutions: 

Single User Solutions Uses dynamic rather than static IP addresses Cannot be used to host a web server Provides one Media access (MAC) address A protocol that controls access from the network interface card to the network media

Single User Solutions (continued): 

Single User Solutions (continued) Ethernet bridge Technology is based on 10 base T cables that connect to a network interface card. Some DSL modems use a separate Ethernet port for connecting to either a single PC or a hub Every Ethernet device has its own unique MAC address The number of PCs supported by a given bridge depends on the number of MAC addresses the bridge can recognize

Multi-User Solutions: 

Multi-User Solutions Provides for many different MAC addresses LANs or DSL bridges Ethernet Routers More sophisticated than Ethernet bridges Can route data to different networks based on packet addresses and protocol rather than hardware Costs are higher than LAN modems, but more feature rich

Routers: 

Routers Main features: Network Access Transmission (NAT) uses private IP addresses from LAN network only accessible from inside local traffic is separated from Internet data traffic security blocks incoming access to local computers Dynamic Host Configuration Protocol (DHCP) Router assigns an IP address to a PC or LAN

DSL Standards Organizations: 

DSL Standards Organizations International Telecommunications Union (ITU) ANSI: T1/E1 Committee ADSL Forum Universal ADSL Working Group, which is going out of business once the commercial roll out of DSL-Lite begins ETSI DAVIC

XDSL Benefits: 

XDSL Benefits High Speed “always on” connections to the Internet and to remote LANs Some DSL technologies can offer speeds up to 8 Mbs Supports virtual organizations Provides a flat rate service

XDSL Benefits (continued): 

XDSL Benefits (continued) Cost-effective Less expensive to deploy than fiber, frame relay, or T-1 services Operates over ordinary 2-wire phone lines Does not require huge upfront costs Users can be added incrementally Workers no longer need to be located on site to gain access to corporate LAN

XDSL Benefits (continued): 

XDSL Benefits (continued) No waiting for connection or busy signals Faster time to market Offers user a dedicated connection as opposed to a shared connection like cable Based on permanent virtual circuits Data can be encrypted without affecting the PVC itself

DSL Competititors: 

DSL Competititors Cable Satellite Wireless

Cable: 

Cable Shared Connection Difficulties in preserving privacy and security requiring the encryption of data Cable networks often do not go into the center of town where most businesses are located.

Satellite: 

Satellite Not a viable option since services are not expected until 2003 or later Direct PC only provides high speed access downstream and not upstream and thus is not a viable option for business users

Wireless: 

Wireless Fixed Wireless LMDS, Winstar/Teligent, MMDS Digital LMDS services have only recently been auctioned and are not expected to be commercially launched until late 1999 in the business market and 2000 in the consumer market Winstar and Teligent are only an option for business users and not consumers. High speed data services have only begun in the last few months

Wireless (continued): 

Wireless (continued) MMDS operators currently offer limited services to consumer marketplace although this will change as the five largest MMDS operators have been bought by either MCI WorldCom or Sprint Will become a competitive threat once integrated into MCI WorldCom and Sprint products

DSL Comparison: 

DSL Comparison

Bandwidth Requirements for Broadband Applications: 

Bandwidth Requirements for Broadband Applications

Bandwidth Requirements for Broadband Applications: 

Bandwidth Requirements for Broadband Applications

Target Markets: 

Target Markets Residential Home Networks Small-Mid sized Businesses, Teleworkers, SOHOs Multiple Dwelling Units Home Networks Shared Tenant Facilities Office complexes Shared Offices

Target Markets (continued): 

Target Markets (continued) Hotels Corporate Campus Environments Hospitals Universities Dorm rooms Class rooms Lounges

XDSL Deployment Hurdles: 

XDSL Deployment Hurdles State of the Local Loop Load coils Bridge Taps Differing wire gauge used in lines Other line quality issues Crosstalk Line lengths

XDSL Deployment Hurdles (continued): 

XDSL Deployment Hurdles (continued) Spectral interference Digital Loop Carriers Older DLCs New Generation DLCs Mini-DSLAMS Power requirements Line Cards Interoperability and Standards

XDSL Deployment Hurdles (continued): 

XDSL Deployment Hurdles (continued) Loop Testing and Qualification No centralized testing mechanism Automated Testing of loops Software Integration Drivers for PCs OSS systems Scalability

DSL Providers: 

DSL Providers ILECs Data CLECs IXCs ISPs

Conclusion: 

Conclusion Explained DSL and the Different Varieties or Flavors of DSL DSL Standards Organizations xDSL Benefits How DSL Compares with Other Broadband Technologies Target Markets XDSL Deployment Hurdles

Slide58: 

Questions, Comments, Suggestions? Thank You Judith Hellerstein, President Hellerstein & Associates 2400 Virginia Avenue NW Washington, DC 20037 Phone: (202) 333-6517 Judithh@tmn.com www.jhellerstein.com