Can't get enough DSL?
Early implementers tout the easy installation and attractive pricing of digital subscriber line service - when they can get it.
By Susan Breidenbach
Network World, 11/16/98
Early digital subscriber line (DSL) adopters, for the most part, give the service top marks, but they have one complaint: DSL needs to be more widely available.
According to telecom consulting firm TeleChoice, only about 825 of the 32,500 central and remote telephone company offices in the U.S. offer DSL; that's about 2.5%. The 825 central offices represent 20 million subscriber lines, but not all of them have been - or in some cases even can be - conditioned for DSL.
Claudia Bacco, a senior DSL analyst with TeleChoice in Dallas, estimates that 50% to 60% of all the copper loops in the country can ultimately support DSL.
Where DSL can be supported, it's a safe bet users will want it. Driven by pent-up demand for high-speed access to corporate networks and the Internet, small offices and telecommuters are snapping up DSL bandwidth as fast as carriers and service providers can provision it.
Cheaper than T-1 and faster and often less expensive than ISDN, the highly reliable technology puts a continuous connection within reach of many who couldn't afford one before. DSL is easy to install and even easier to upgrade. Instead of requiring hardware or software changes at the customer site, carriers can provision higher speeds with a flip of the switch.
Given the user demand, the relative ease of provisioning and the myriad potential providers, it appears there's no need to worry that DSL might parallel the slow and troubled deployment history of ISDN.
Speedy video
Vazda Studios of Birmingham, Ala., recently began using DSL to expand its business beyond the local area. The post-production facility assembles various elements into digital video television commercials and has traditionally kept local courier services busy exchanging computer disks and VHS cassettes with the firm's clients. One small graphic component might be 10M bytes to 15M bytes, making transmission via modem too slow to contemplate, says Bob Askew, chief engineer at Vazda.
Askew experimented with asymmetric DSL (ADSL) at his home when BellSouth began testing the service early this year. He then implemented ADSL in the office when the technology became commercially available this fall. Now customers can send Vazda graphics via the Internet, with DSL speeding up downloads.
Vazda gets ADSL from WWISP, a local ISP that resells BellSouth ADSL service. WWISP charges about $250 per month for a line with a maximum speed of 1.04M bit/sec downstream and 256K bit/sec upstream, Internet access, a static IP address and DSL router rental.
Askew's only real complaint is that BellSouth's DSL deployment to date is limited to DSL.Lite, a slower version of ADSL based on the new G.Lite standard.
"Right now, when we finish a commercial we have to make a VHS tape and use a courier to deliver it to the client for approval," Askew says. "If we had 8M bit/sec bandwidth combined with MPEG compression, we could let clients retrieve the video from our server for review." This would save time and let the company expand its client base geographically.
Like Vazda, many other early implementers are enjoying the benefits of DSL. "It's been incredibly easy to implement - almost plug and play," says Gary Welsh, president of Welsh Consulting, a network integrator in Boston. Welsh has helped the ISP Shore.Net deploy the service to some of his clients.
Carl Hu, the group program manager for Microsoft's public network projects team, is already spoiled by ADSL. Microsoft began testing GTE's DSL services more than two years ago, and now has about 1,000 employees using ADSL lines to telecommute to corporate headquarters in Redmond, Wash. Speeds range from 1M bit/sec to 6M bit/sec downstream and from 64K bit/sec to 2M bit/sec upstream.
But Hu recently moved from a house across the street from the GTE central office that serves the Microsoft campus to a new home on a different GTE loop. He's back in dial-up mode and chafing under the bandwidth constraints.
Implementation advice
Many DSL problems were ironed out during extensive pilot tests over the past few years, Hu says. Applying lessons he learned from Microsoft's DSL rollout, Hu advises telecommuters to ensure the IP stack in their PCs is configured to use the Dynamic Host Control Protocol and their service providers are set up to support DHCP.
Simply determining whether you can get DSL at a particular location may be your biggest implementation problem. Some phone companies have databases with availability information on their Web sites, but the databases are often wrong, says Robert Palmer, president of Problem Solvers Interactive, a computer consultancy in Birmingham.
If you're fortunate enough to live in an area where DSL is available, examine all the service options before you choose one. Be sure to avoid unnecessary equipment rentals, read the fine print about performance and shop around if you need a static IP address.
Page Law Firm in Birmingham jumped onto the DSL bandwagon this year to speed online legal research. The company replaced dial-up ISDN access and dynamic IP addressing with an ADSL bundle from WWISP that includes a static IP address.
"We were initially set up with a router that cost an additional $130 a month," says Rick Honsberger, Page's network administrator and president of its Controllex subsidiary, which develops case management software. "I suspected that since we had a proxy server, we didn't really need a router, and that turned out to be true."
For $140 per month, Page gets a maximum bandwidth of 1.5M bit/sec downstream and 256K bit/sec upstream, a DSL modem and one static IP address.
"We're experiencing close to maximum speeds during off-peak hours, but only about a quarter to half of that when the network is busy," Honsberger says. Even so, "the speed is wonderful."
Some carriers don't offer static IP addresses with DSL services, which might be part of their attempts to protect T-1 revenue. If you need a static IP address for your site, check with alternative service providers and compare rates.
However, static IP addresses raise security concerns because DSL is a persistent connection. The door is always open, and you're sharing a router port at your service provider's facility with other customers. Unlike plain old telephone service and ISDN lines, DSL doesn't provide a secure point-to-point connection. And a permanent address makes it easier for cybercrooks to find you.
In single-user telecommuter installations, it's best to stick with dynamic addressing. Also, keep in mind that today's desktop operating systems have a lot of built-in network capabilities. Hackers can use these facilities to gain access to Internet-attached PCs, so be careful how telecommuters' hard drives are set up for sharing, and limit the availability of IP ports.
It's not possible to disable sharing mechanisms in LAN environments, so heavy-duty firewall protection is essential. "Don't put your firewall/proxy server in the same box as your main file server because you don't want that server on the Internet," Palmer cautions. "A lot of people are doing that and don't realize what can happen." To plug this hole, Problem Solvers Interactive developed a Linux-based firewall that can double as a router and connect up to 253 devices to a DSL line.
A grain of salt
Despite the glowing reviews of DSL services, there is still a lot of uncharted territory. Performance is great now because there aren't many subscribers, but it remains to be seen whether users will be able to get near the maximum bandwidth rates as new users pile onto DSL nets.
DSL coverage is still scanty, especially as you move away from big metropolitan areas. The new G.Lite standard for ADSL may help the technology proliferate because it's easier to install. However, there are still several issues to resolve.
"G.Lite could allow for more rapid ADSL deployment because the phone companies wouldn't have to send a technician out to install splitters at every residential or business account they want to open," says Lisa Pelgrim, a senior analyst with Dataquest, a market research firm in San Jose, Calif. "But it's still in a test mode or early adoption phase."
DSL is also by definition a copper-only technology that can't be deployed in subloops that are connected to the central office via fiber. Service providers are coming up with hybrid ISDN/DSL services, called IDSL, to address this problem, but IDSL falls far short of full DSL capabilities. For example, the maximum speed of an IDSL connection is 144K bit/sec.
Availability problems, coupled with standards issues and the lack of a single national DSL provider, make it difficult for a large organization to implement DSL networks. "If you're a network manager in a big company, you don't want to deal with a lot of different providers and manage a lot of different types of services," Pelgrim says.
Moreover, while DSL users so far report smooth sailing, these trial populations are generally skewed toward the more tech-savvy users. And early adopters tend to get lots of attention and handholding from vendors and service providers.
"If the service provider comes in and does all the customer-premise installation and configuration - opens the PC, installs the Ethernet card and configures the software - that's one thing," TeleChoice's Bacco says. "But if they just install the line and leave all the rest of this to the customer, a lot of people are going to have problems."
That said, the entry level for DSL is low enough that you might as well exploit it where it's available, as long as security concerns are addressed.
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