Internet users know this simple equation by heart: speed = money. The faster the access, the more it costs. And for businesses that really need to connect an office network to the Internet or host a busy Web site, nothing beats T1.

But T1 is a budget buster. Installation can easily cost $5,000, with monthly fees for full T1 access at 1.544 megabits per second (Mbps) running to $2,500. T1 is also a pain to set up and manage, usually requiring help from IS staff or expensive outside contractors. That's why many small and even midsized businesses shun T1.

But what if someone offered an online service that promised the speed of T1, the cost of ISDN, and the simplicity of analog modem dial-up? That's what digital subscriber lines (DSL) promise.

For businesses that can't afford the price or hassle of T1, DSL can offer enormous benefits. After much foot dragging, even the baby Bells (which invented and promoted the first DSL-like service, ISDN) are starting to boost DSL service. They've no doubt been spurred by the success of Competitive Local Exchange Carriers (CLEC), like Covad and NorthPoint, that hit the market first with DSK service, and by cable companies offering multimegabit Internet access to consumers. Not surprisingly, more and more ISPs (such as Concentric and Epoch) are offering matching Internet access, at speeds ranging from 128Kbps to 1.544Mbps. DSL is a logical choice for small businesses, telecommuters, and even home users, especially those who can't get cable Internet access.

DSL has even more advantages. Unlike ISDN, DSL isn't metered by the minute. Better yet, DSL is truly an "always on" service, which makes it suitable for a wider range of applications, including interconnecting LANs, small Web site hosting, videoconferencing, and connecting branch offices.

Not surprisingly, DSL use is expected to boom. According to market research analysts at TeleChoice (www.xdsl.com), the number of installed DSL lines will grow from 39,000 in 1998 to 904,000 in 2000 to 2.35 million by 2002. "DSL will do well among people working at home and in urban areas where cable services are not widely deployed," says Claudia Bacco, TeleChoice's senior DSL analyst.

Although the number of companies supplying DSL service and Internet access is increasing, would-be users face a confusing range of choices about availability, price, equipment, and configuration. DSL service is hardly ubiquitous. Even in areas where DSL has been deployed, if you're too far from the phone company's central office (where the switching hardware is located), you can't get it or you don't get the maximum possible speed. Prices, while reasonable for businesses, are steep for individuals. 128Kbps service can cost as little as $89 per month, while 1Mbps to 1.544Mbps service can go for several hundred dollars. Equipment is not widely standardized, and there are a number of DSL variants to contend with. (See the table, "The Many Flavors of DSL," below.)

INSIDE DSL

DSL is a generic term for a whole family of services, often referred to as xDSL. The service you've probably heard the most about is Asymmetric DSL or ADSL. As the name implies, data flows more quickly in one direction than the other--in this case, the "downstream" direction toward you. In symmetric DSL, the speed is the same in both directions.

DSL setup is pretty familiar. Instead of requiring a special line, DSL relies on the installed, twisted-pair wiring used for standard analog phone service. You connect the line to a special DSL modem, which in turn is connected to an Ethernet card in your PC. (In a network setting, you'd obviously connect the line to an appropriate DSL router and then to your server.) Although DSL is primarily intended to carry data, some versions, such as ADSL, can also carry voice. That means you can have the DSL modem, phone, and fax machine all sharing the same line. Just like with ISDN, you could carry on a conversation and download a file at the same time over the same line. Another similarity is that the DSL service is provided by a Bell or a CLEC like Covad, and the Internet access is provided by an ISP. However, you'll typically order the whole shebang from an ISP, who will call in the line installer and provide you with the modem and Ethernet card.

Current DSL offerings span the range, but ADSL has gotten a lot of attention for a couple of reasons. First, it's the cheapest DSL around. Second, it accommodates voice. (The other DSLs typically carry only data.) Third, ADSL was designed with video-on-demand in mind, so it's fast and a good fit for Web surfers.

How so? Back in the early '90s, Bell Labs had the notion that video-on-demand services--movies, videoconferencing, and so on--delivered via existing copper lines, would be all the rage. Customers would send a few remote control signals upstream--select this movie, pause, play, stop, and so on--and would receive a torrent of movies and video data. Traffic on such a system was asymmetric, meaning users would receive more bits (downstream) than they sent (upstream).

Video-on-demand never took off, but the Web did, and ADSL turned out to be a great way to ship lots of data over existing phone lines. The trick? Data is sent at frequencies higher than those used for voice. A bigger chunk of bandwidth is also devoted to data, so a lot of data can be sent. (Voice is carried at frequencies of less than 4KHz; DSL transmits data at 26KHz and above, well beyond the range of human hearing.) As a result, a single phone line can carry both voice and data. Think of it as a bridge carrying automobile traffic on one deck and trains on another. The trains and cars don't interfere with each other, even though they're both traveling over the same structure.

Keep DSL's downsides firmly in mind. Although ADSL boosters talk about 8Mbps downstream speeds, the reality is far humbler. For example, typical low-end ADSL service starts at speeds of 384Kbps downstream and 128Kbps upstream, with the fastest ADSL service operating at 1.544Mbps. DSL also has distance limitations, ranging from 1,000 feet from a Bell central office (for VDSL) to 17,500 feet (for ADSL). Worse, speed falls off the farther you get from that central office. So before you sign up, make sure your provider spells out in writing exactly what speeds you'll be getting.

REALITY CHECK

DSL isn't a T1 killer. But for businesses that can't lay out a couple grand per month and need to connect a LAN to the Internet, host a small Web site, or accommodate telecommuters, DSL is an excellent solution.

"We're paying under $500 per month for what would usually cost close to $2,000 per month," says Mel Bracken, director of IT for AdAuction (www.adauction.com), a San Francisco–based online advertising broker that connects its office LAN to the Internet using 1.1Mbps service from DSL net works (www.dslnetworks.net) and Covad Communications.

Instead of paying $1,500 to $3,000 for T1 installation and equipment, Bracken got DSL service up and running for under $500. And while the T1 waiting list was three months long, DSL was installed in less than a month.

"DSLnetworks has been astute and made it a one-stop shop," Bracken adds. "We've had only one failure--for 15 minutes--and that was caused by a bad network card."

Other businesses report similar experiences. Employers' Medical Network, a Sacramento-based medical insurance processing service, pays $199 per month for a 416Kbps connection provided by Concentric (the ISP) and NorthPoint (the DSL line provider). The company uses DSL to allow customers to access the company's Web-based applications. Company CIO Keith Waldorf explains, "We wanted to expand what we could do on the Internet without paying $1,200 per month, plus the installation and equipment fees for a T1 line."

"Compared to DSL, ISDN is terrible--it's down all the time and a nightmare to configure," adds Waldorf. "With DSL, you install it by plugging it into the wall. As far as maintenance and management, it has been a piece of cake. We're never going back to dial-up or ISDN."

BUYING DSL SERVICE

DSL sounds pretty straightforward, and in most situations, it is. But choosing the right ISP/provider combination requires some homework.

Just as dial-up users pay their local telephone company for a phone line and their ISP for Internet service, DSL users must sign up with both a DSL provider and an ISP. In practice, most DSL providers partner with ISPs or also provide Internet service, so you get a single bill.

Availability. Unfortunately, even if DSL service is available in your area, it may not be available to you. Not only must you be in an area served by a DSL provider, but your telephone company must also support DSL. In addition, you must be within a certain distance of the central office--usually 17,500 feet, though variants of IDSL can work at distances of up to 36,000 feet.

How do you find out if you can get DSL? Some DSL providers or their partner ISPs let you fill out an online form and get an answer more or less on the spot. For example, supply PacBell's Web site (www.pacbell.com/products/business/fastrak/dsl/dsl-availability.html) with your phone number, and it can tell you if "DSL is likely to be available in your area at this time." To get the final word, however, you'll have to call and provide your address. In many cases, confirmation may take several days.

DSL availability information for Covad can be found on an interactive page at www.covad.com/telespeed/availability.html. Rhythms at www.rhythms.net/connect/avail.html has a rather vague map of available service. NorthPoint can't give you the scoop on the spot, but if you enter your information at www.northpointcom.com/getdsl/index.html, the company will respond within 24 hours.

Cost. If service is available, the next consideration is cost, which varies depending on the type of DSL service you buy (say, ADSL versus IDSL), connection speed, usage, the number of IP addresses you want, installation and equipment fees, and, of course, the provider. Don't hesitate to shop around. You'll find that ISPs partnered with the same DSL provider often offer different services and pricing schemes.

At the low end, you can get ISDN-like speeds and one IP address. Pacific Bell, for example, charges $59 per month for the ADSL line and $30 per month for 128Kbps Internet access. At the high end, Brainstorm Networks charges up to $250 per month for a 1.544Mbps, T1-equivalent ADSL line (supplied by either Covad or NorthPoint) and up to $175 per month for Internet service, which includes 32 IP addresses. The kicker? Only the first gigabit of combined upstream and downstream traffic per month is included. Any use above that--a whole or even a partial gigabit's worth of traffic--will cost you $5 per gigabit. So before you sign up with any service, ask about usage caps and how the provider rounds up partial usage. That can make a huge difference in your bill.

Charges for IP addresses also vary. Brainstorm throws in a bunch with its service; other ISPs charge incrementally. For example, DNAI charges an extra $10 per month for five IP addresses and $50 per month for 29 addresses. You can avoid these charges by using Network Address Translation (a.k.a. IP Masquerading), which lets a single IP address serve many networked users. For companies and individuals with very small LANs, NAT is one way to save $10 to $50 per month.

Pick the right kind of DSL. The DSL service you pick--ADSL, SDSL, IDSL, and so on--should be dictated by what you need to do with the connection. If your company needs to host a corporate Web site, you should probably opt for a symmetric DSL service, such as SDSL. Symmetric services typically offer faster upstream speeds and that's what you want--the ability to pump out data on your Web site at high speeds. The downside is that symmetric services may have onerous usage caps and charges.

If your company mostly wants to provide the office network with speedy Internet access and e-mail service, an asymmetric service like ADSL may be plenty. If e-mail is your primary need, you may find a low-speed (128Kbps or 144Kbps) connection to be more than enough.

If your company is setting up a telecommuting program, you may want to purchase DSL service without the associated Internet access, using the DSL service to directly connect employees to your office. Access would be speedy, and telecommuters could get onto the Internet via the office's existing connections.

Very small offices on a tight budget should weigh the advantages of getting an ADSL service that also supports voice. This lets your phone, fax machine, and DSL modem share the same line. If you buy ADSL service from your local Bell, voice service is usually included; if you pick an ISP/DSL provider combination, it usually isn't.

Pick the right DSL provider. What if two or more DSL providers (like PacBell, Covad, and NorthPoint) service your area? Which one should you pick? First consider the DSL services offered. If you need symmetric service for hosting your Web site, pick a provider (and the appropriate ISP) that has it.

Next, think distance. The range of DSL providers differs. For example, in the Bay Area, Covad's IDSL seems to stretch a wee bit farther than ADSL service from other companies. (It's a matter of speed and distance. IDSL is slower and the signal can be carried farther.) Ask if there's any speed drop-off the farther you are from the central office.

Next, should you choose a PacBell-like provider (which offers both DSL service and Internet access) or a CLEC/ISP combination? PacBell has two big advantages: It provides regular telephone service with its ADSL, and if something goes wrong, you have just one company to deal with. If you buy from a CLEC/ISP duo, a problem might be the fault of the ISP, the DSL service provider, or PacBell, which still owns the wires. In such a situation (since Bell and the CLEC are competitors), there may be more finger-pointing than problem-solving.

On the other hand, I suspect CLECs and ISPs are savvier about data networking. ISPs may also be better at babying newbies. ISPs have to be very service-oriented, since they may deal with consumers dialing in at 28.8Kbps and businesses connecting to the Net via T1. CLECs such as Covad also have a national presence of a sort. If your company has offices across the country and you want to deal with one vendor, a CLEC may be the best way to go.

Pick the right ISP. Let's say there's only one DSL provider servicing your area, but it has a number of ISP partners. (Covad, for example, has arrangements with more than 30 ISPs.) Which one do you pick?

Naturally, examine the ISP's installation and monthly fees, and ask about included hardware (from modem to Ethernet card). Find out if usage is truly unlimited or if there's a cap and additional fees. You may find significant price differences. Check out the extras, too. Some ISPs offer special packages to businesses that need VPN (virtual private networks), security, 24-hour support, and more.

No matter how big your company is (and no matter how simple DSL is), service and support are still big issues. How quickly can the ISP set up your account? If your DSL line dies, what will the ISP (and its DSL provider) do? Is support available 24 hours a day? Can you get help via phone and e-mail? What's the turnaround time on questions and repairs? Does the ISP (and its DSL provider) offer any service guarantees? For example, if access drops below a certain speed or an outage lasts longer than 15 minutes, will the ISP or DSL provider issue a refund or credit your account? Ask for the details up front and in writing, if you can, but don't be surprised if most DSL vendors can't or won't provide it.

While you're at it, ask the questions you'd ask an ISP that offers old-fashioned dial-up access. How many incoming DSL lines does the ISP have? What's the ISP's connection to the Internet "backbone"? Some smaller ISPs may have only T1 connections, which means they'll choke as the number of users climbs. For the best performance, an ISP should have multiple T3 (45Mbps) or OC-3 optical (155Mbps) connections to the backbone. In fact, the ISP should have connections to different backbones as a safety net, especially if it has a lot of customers.

It's also pertinent to ask if the ISP (or the DSL provider) is oversubscribed. In other words, how many customers use the service? You might also consider picking an ISP that offers DSL service from multiple providers, in case you want to switch.

Experience with the technology counts, too. An ISP that's been offering ISDN and T1 access for several years--versus an ISP that's done only analog dial-up--probably has a better technical background for implementing DSL.

Remember that reliability, service, and experience are a little hard to gauge. DSL is still new, and DSL providers and ISPs have not yet been tested by independent organizations such as Boardwatch Magazine (www.boardwatch.com) or Keynote Systems (www.keynote.com). If you want some real-world input on DSL providers and ISPs, check Usenet groups devoted to telecommunications, such as ba.internet. You could also go to Deja News (www.dejanews.com) and search for DSL or a vendor's name. You'll get a screenful of advice, opinions, complaints, and more.

HARD FACTS ON HARDWARE

DSL modems and routers aren't quite like their dial-up and T1 counterparts. For example, you can dial up most ISPs with almost any 33.6Kbps modem and connect. That's not quite the case with DSL, which has a squadron of largely incompatible offerings. In most cases, an ADSL modem won't work on an SDSL setup or an HDSL router on an IDSL line. And depending on the DSL service, stepping up to a faster speed (say, from 384Kbps to 1.1Mbps) from the same provider, using the same type of DSL, may require a different modem. That's why it's often best (and often required) to buy or lease hardware from your service providers.

But change is afoot. A new kind of ADSL called G.Lite (also known as Universal ADSL or DSL-lite) promises to simplify things. Backed by standards organizations and a huge number of vendors, G.Lite promises to be user-installable, compatible with voice, and cheap. It will also eliminate the need for "splitters," special filters that segregate voice and data. If G.Lite succeeds, it will let everyone--users, ISPs, and DSL providers--standardize on a single approach. Watch for it in 1999.

At this point, the most fundamental choice is selecting a DSL modem or router. Modems typically support one IP address; routers are designed to provide service to small networks. DSL modems usually run about $400 and come from Alcatel, Copper Mountain, Hayes, and other vendors. Routers sell for $500 and up, and come from manufacturers such as FlowPoint, Cisco Systems, and Net to Net Technologies.

If you want to add lots of DSL telecommuters, plan on switching DSL types or speeds, or expect to relocate in the near future, you may want to lease equipment. Expect to pay about $25 per month for a modem and $40 per month for a router. "If you are not technical or you have a small company with no IS staff, then leasing and managed service [where the provider installs everything for you] can make sense," AdAuction's Mel Bracken notes. "Otherwise, buy the equipment."

If you're upgrading from ISDN, you might want to consider IDSL service. With IDSL, you can use your existing ISDN equipment, such as the Ascend Pipeline 50 and Pipeline 75 routers. On the downside, connection speed is limited to 144Kbps.

Although most DSLs use standard phone lines, your business or home might need some rewiring (a task best left to your DSL provider). "My office is in an older complex built in the late 1970s, and the wiring is original--the communications closet is a mess of old lines," says Keith Waldorf. "But the installer walked in with a DSL modem, plugged it into a wall jack, and it was up and running. So there is hope for businesses with old wiring."

INSTALLING DSL: ONE MAN'S STORY

Having suffered through an ISDN installation a few years ago, I expected ADSL to put me through the wringer. Instead, the installation was easy and went so smoothly that I had my Web server up on the Net within 15 minutes of the service technician's departure. Fourteen of those minutes were spent oohing and aahing over the faster response time.

Vendors do tend to put their best foot forward when installing products and services for the press. (My PacBell line was set up within two weeks. You'll probably have to wait longer--maybe a lot longer.) Getting the 384Kbps upstream/1.544Mbps downstream connection involved a short conversation with a service representative, who determined that service was available, offered a choice of services, and scheduled an appointment with the installer.

Line installation took two visits. First, a PacBell technician showed up and verified the quality of the line between my house and Bell's central office. The next day, a contractor came and drilled a hole in the wall, ran a wire to the outside terminal box, installed a jack, and tested the connection with his laptop. If you don't have an Ethernet card in your PC, the technician will install that, too. The whole thing took about an hour. If I'd had an existing line, it would have been quicker.

There was a 20-minute delay when the technician called to get the service turned on at the remote end, and then, voilà! near-T1 service, priced at $250 per month. There were no hassles with configuring the service or equipment. (If you have ISDN, T1, or other services installed nearby, you may not be able to use DSL due to interference.) The technician gave me a list of parameters to enter in my Network control panel, namely, my IP number and addresses for my gateway and DNS (domain name server).

It's clear that ADSL is a good choice for hosting a Web site. With ISDN, your provider must "wake up" your line before anyone can access your server. ADSL, on the other hand, is always on, with no billing by the minute. That makes it suitable for Web servers, instant messaging, Internet paging services, and so on.

Just remember that while DSL can get you on the Web faster, it can't overcome Internet traffic jams and underpowered Web sites you're visiting. Still, when the info highway clears a bit, DSL's big pipe is a kick. I was able to watch a conference using RealVideo without the usual hiccups, stalls, and crashes. And of course, downloading files is much less of a chore. Need a new version of Netscape Communicator? I downloaded the latest 14MB behemoth in just over a minute.

DSL is perhaps pricey when compared to cable Internet access. But cable service isn't widely available (especially in business districts) and ADSL is.

POTHOLES IN THE ROAD

DSL sounds like a dream, and when it works right, it is. Cruise some Usenet newsgroups and you'll discover plenty of complaints, though, especially when it comes to ISP service and support.

Part of the problem is that DSL is new, and ISPs are still getting a handle on the technology. None of the various DSL flavors are compatible, and some are implemented in radically different ways. Internet cable companies love the confusion. @Home Networks crows that "40 ADSL equipment makers sell six versions of ADSL in two incompatible modulation ‘standards.'"

Alas, 'tis true. There are two ADSL camps, each supporting different modulation techniques, called CAP (Carrierless Amplitude/Phase modulation) and DMT (Discrete MultiTone). CAP is somewhat more widely deployed and is supported by many DSL hardware vendors. DMT is supported by the American National Standards Institute and is used by the potentially very popular G.Lite service. It sounds like a replay of the VHS and Betamax wars. Here's hoping a standard emerges.

THE LAST MILE

DSL is only one of a number of solutions to the challenge of providing a high-speed "last mile" connection from the phone company's central office to your office or home. In a way, DSL is the telephone industry's response to the threat posed by cable, satellite, and broadband wireless services. It's also a way to squeeze the last penny from Bell's copper lines.

Ironically, the leading providers of DSL, the telephone companies, may have the most to fear from the service. If DSL services begin to cannibalize their T1 market, profits are sure to suffer. "The telephone companies' T1 business is growing and their profits are huge," says Bob Metcalfe, who invented Ethernet in 1973 and founded 3Com in 1979. "Small surprise--they have a monopoly on the T1 market. That is the number-one deterrent to speedy DSL deployment."

Nevertheless, older, more expensive, and highly profitable services like T1 aren't likely to remain competitive. "I currently pay $600 per month for leased 56K Internet access, but a cable modem is $40 per month," Metcalfe says. "When DSL modems and central office equipment are shipping in volume, the cost to DSL providers should be $10 per month." That should mean bargain-basement prices for end users.

But DSL's rosy future is not a given. It's been 10 years since ADSL was first proposed, yet it and other DSL technologies are still wet behind the ears. They lack some of the refinements of T1 service, such as comprehensive service level agreements and universal standards. Some early adopters have had unexpected problems, and DSL is not cheap enough to appeal to consumers. (Oddly, DSL is more expensive in California than in many other parts of the country.)

Still, it's clear that DSL fills a huge void. It's faster than ISDN, cheaper than leased-line services such as T1, and far, far superior to standard analog dial-up. Equally important, it supports a range of applications, such as Web hosting, videoconferencing, and remote backup, that until now have only been practical using T1. For small and midsized businesses, for branch offices, for telecommuters, and for others who work at home, DSL may well make T1 history.

© 1998 Jeff Ubois. All rights reserved.

Jeff Ubois has been covering the Internet and telecommunications for 15 years. He has written for Internet World, Digital Media, MacWeek, Wired, the New York Times Syndicate, Technology Access, Computer Security News, Bloomberg Business News, and others. He can be reached at jubois@netcom.com.

High-Speed Services Compared

  ISDN T1 DSL Speed 128Kbps 1.544Mbps 128Kbps to 1.544Mbps Cost per month (including Internet service) $60–$120 for moderate usage $800–$2,500 $89–$425, depending on speed Notes Per-minute charges make full-time connections impractical Price can vary with mileage, usage, and service level Wide spectrum of services; distance limitations; incompatible versions

The Many Flavors of DSL

    ADSL Asymmetric digital subscriber line. The most common standard, it theoretically offers 1.5Mbps to 8Mbps downstream and 16Mbps to 640Kbps upstream speeds.     HDSL, HDSL2 These two high data rate DSLs are symmetric services capable of 1.5Mbps and 2.048Mbps speeds, respectively. HDSL requires two or three wire pairs; HDSL2, just one pair. HDSL2 has been announced but not deployed.     IDSL ISDN DSL. Similar to ISDN, it allows you to use existing ISDN equipment. But the maximum speed in both directions is 144Kbps.     RADSL An asymmetric service, rate adaptive DSL promises to provide between 600Kbps to 8Mbps downstream and 128Kbps to 1Mbps upstream speeds, while offering simultaneous voice service. RADSL can dynamically adjust to line conditions. RADSL is just beginning to be deployed.     SDSL Symmetric DSL, a popular alternative to ADSL, is offered by NorthPoint and various ISPs. The service promises two-way 768Kbps access.     G.Lite (UADSL/DSL-lite) Due out next year, G.Lite will be user-installable and provide speeds of 1.544Mbps downstream and 512Kbps upstream. Backed by many hardware vendors and the Universal ADSL Working Group.     VDSL The fastest and newest DSL on the block, very high speed DSL is an asymmetric service, offering speeds of 12.9Mbps to 52.8Mbps

DSL Resources on the Internet

A number of excellent resources on the Web describe DSL markets, technologies, and services.

www.adsl.com
The ADSL Forum site has a number of FAQs and a thorough list of service deployments and trials.

www.xdsl.com
Probably the largest compendium of general information about DSL. It is maintained by TeleChoice, a market research company, and offers articles, background, and market-oriented information.

www.uawg.org
Home of the Universal ADSL Working Group, developers of G.Lite. Focus is on the development and deployment of UADSL.

www.dnai.com/~dfannin/adsl/
A how-to site on ADSL and Linux, by David Fannin. The best step-by-step guide to DSL installation and to Linux configuration for DSL.

www.thekrib.com/dsl.html
Home to "Diary of Pain: My continuing DSL saga" by Erik Olson. The dark side of DSL--a tale of incompetence and woe involving U.S. West.

www.cs.tamu.edu/people/jhamann/adsl/node4.html
Good coverage of technical aspects of ADSL. A little dated, but if you want to know how it really works, go here.

comp.dcom.xdsl
Search the archive of this Usenet newsgroup for true tales of DSL installations, solutions to common problems, and devious hints such as "Sign up with PacBell's Internet service when you order DSL from them, so you get the free installation. Then declare your dissatisfaction with their Internet service, and switch to whatever ISP you want."