Users can save money setting up frame relay and ATM networks by using DSL access links rather than more expensive 56Kbps or T-1 lines.
Supporting speeds from 144Kbps to 7Mbps for downloads, DSL is as fast or faster than competing technologies, and providers say they can offer it at prices hundreds of dollars less per month.
AT&T Corp. and WorldCom Inc. offer DSL as options to their frame relay and ATM services, and Sprint Corp. and Verizon Communications Inc. say they are considering it. And while the recent woes of DSL service providers make users nervous, some find that DSL offers the only affordable way they can set up the networks they need.
AT&T’s DSL Access to Frame Relay Service, for example, made it possible for a chain of tire stores and a chain of movie theatres to tie their nationwide sites in to their corporate headquarters.
“Without DSL, the price wouldn’t have fallen into where I needed it, and the whole project might not have flown,” says Harry Fikentscher, director of IT for Morgan Tire, based in Clearwater, Fla. Morgan Tire is using DSL to connect 79 of 443 sites to its frame relay network. The savings that DSL represented kept the average monthly cost per access line on his network using a mix of DSL, 56Kbps and T-1 access to US$125, which fit into his budget.
Similarly, Sony Leows Theaters use 100 DSL lines to connect theatres to the corporate frame relay network to coordinate ticket sales, give e-mail access and remote monitoring of network gear in the theatres.
“Cost, cost, cost,” is the reason the theatres use the technology, says Fred Huber, Sony Leows’ IT director. He would not have had enough in his budget if he had to spend up to US$325 per month for 56Kbps lines rather than US$170 per month for 144Kbps DSL connections.
Even so, users should know DSL has not been without pitfalls. Huber says he had 50 of his theatres hooked up using DSL from a provider called Zion Communications, which in turn subcontracted with NorthPoint Communications to install the DSL circuits. When NorthPoint went belly up, he lost all the lines. It took two weeks to switch them over to AT&T.
“DSL is a good sell on price, but I think people are still scared about its reliability,” says Pat Hurley, an analyst at TeleChoice. This year, all three of the major start-up DSL providers, Covad Communications Co., NorthPoint Communications Group Inc. and Rhythms NetCommections Inc., have filed for bankruptcy protection. WorldCom bought up Rhythms leases on space in 709 local carrier switching offices, indicating its interest in the technology. SBC Communications has bailed out Covad at least for the next year.
Because DSL runs over regular phone lines, these wires must be leased from the local, regional Bell operating companies. Some frame relay providers also get DSL connections installed by other providers, making it hard to assure service quality.
“Service-level guarantees are not as comprehensive for DSL,” says Randy Rector, manager for WorldCom’s frame relay and ATM services, which offers a DSL option called Enterprise DSL. Some local providers that own the actual copper loops used to carry DSL only staff their repair services from 8 a.m. to 5 p.m. Monday through Friday. That means WorldCom can’t offer a 24-7 repair guarantee in these locations, he says.
The average time to repair a downed DSL link is 24 to 48 hours, says Alan Benway, an AT&T product manager. That amount of downtime would be unacceptable for a T-1 link but might be OK for a DSL link, especially considering the price. Also, network delay can be longer, Benway says.
But in practice, Huber and Fikentscher say they see no difference in service quality between their DSL lines and 56Kbps lines.
The need for 56Kbps lines points up another problem with DSL: It’s not available everywhere.
The speed that DSL supports varies depending on the quality of the line and the distance to the switching office. In some cases, DSL is unavailable altogether because customer sites are too far away from a central office.
By contrast, 56Kbps data lines and T-1s come with consistent bandwidth guarantees, regardless of distance. Under ideal conditions, DSL supports downloads up to 8Mbps.
Problems delivering DSL are less related to the technology than they are to the business structures under which the service is offered, says Steve Taylor, principal with Distributed Networking Associates Inc. of Greensboro, N.C., and a Network World (U.S.) columnist.
Another service provider than the frame relay carrier, which adds a separate layer to managing and maintaining the service, generally provisions the lines for DSL. “There is nothing intrinsically that would make DSL less reliable,” Taylor says.
Even so, potential users may balk at using DSL, and providers sometimes offer to substitute other links for free if the DSL proves inadequate. “I was very leery of it, but AT&T said it would provide us connections to sites, either DSL or frame relay, at the DSL price,” Fikentscher says.
Some customers adopt DSL access to frame relay as an alternative to another inexpensive way to network many small sites – VPN. For a company that already has some frame relay links, adding sites via DSL requires learning no new technology. With an Internet-based IP Security VPN, users would have to buy new equipment and learn how to use it, AT&T’s Benway says.
Despite limitations, there is room for providers to offer some service-quality levels. WorldCom offers DSL access to its frame relay and ATM services with three different levels of service priced differently. A 128Kbps DSL line with the lowest service class costs US$200 per month. A 1.5Mbps line with the top service quality costs US$1,500 per month. Other speeds and prices fall in between these rates.