Once and Future DSL

To divine the future of DSL, think of the technology not as a service, but as a transport mechanism able to wring valuable bandwidth from a single copper pair.

To divine the future of DSL, think of the technology not as a service, but as a transport mechanism able to wring valuable bandwidth from a single copper pair. After all, says Edge Connections CEO Jim McKenna, High-bit-rate DSL technology is already used to leverage two copper pairs into 1.5 megabits per second of bandwidth for T1 customers.

"The greatest opportunity in telecommunications exists not in metro optical, not in Gig-E [Gigabit Ethernet]. Its not in the fantasy that Moores law is going to continue forever. Its in the reality that small and medium businesses have not seen any benefits of broadband, and in that carriers havent taken advantage of the inherent value of twisted copper pairs," McKenna says.

Edge Connections is an Atlanta competitive carrier that provides service primarily to multitenant buildings.

Some competitive carriers have been quick to adopt strategies to deliver voice and data bundles using DSL, but observers expect the regional Bells that initially dragged their heels deploying the service a year ago to begin pushing through the pack with widespread deployment of residential service.

According to McKenna, the key is moving the technology closer to the edge of the network, a strategy being played out in SBC Communications $6 billion Project Pronto, which is upgrading digital carrier loops to put the DSL gear closer to the customer. The magic is in dynamic bandwidth management. A small business with eight phone lines typically uses only about 25 percent of the capacity at one time. "Enter a new use of old technology: DSL. We can dynamically allocate that pipe, all or in part, to voice or data," he says.

Heres how it works: Edge Connections puts the DSL Access Multiplexer in the basement, and an integrated access device manufactured by Polycom sits in every office. A Jetstream Communications CPX 1000 in the central office prepares voice and data for transmission to the building on a fat pipe, or back onto the public switched telephone network.

"Voice is really the driver for profit," says Manish Gupta, Jetstreams vice president of marketing. "Data alone does not meet the economic criteria for investing in a new implementation."

Bells worried about running out of copper as well as interexchange carriers that are facing the certain loss of their long-distance customers have begun to consider DSL as a defensive strategy. A DSL-based service bundle may keep AT&T, Sprint and WorldCom long-distance customers from defecting to a regional Bell. Bells facing the dilemma of whether to roll out more local loops could use DSL to leverage existing infrastructure, Gupta explains.

As is true with all network upgrades, the decision to make DSL available to the masses will be driven by economics.

Catena Networks two broadband access systems — the CNX-5 Broadband Asymmetric DSL System for upgrading digital loop carrier systems and the CN1000 Broadband Loop Carrier — combine voice and data on a single port. The systems can be remotely provisioned, eliminating the need for truck rolls and driving down the cost of provisioning new DSL service.

"We believe that people want dial tone and lifeline services and we allow service providers to converge the voice and data together, without the subscriber knowing the difference," says Gary Bolton, Catenas vice president of product marketing.