Cooperative effort: Copper Mountain launches interoperability program for symmetrical DSL

Digital subscriber line vendor Copper Mountain Networks is initiating an interoperability program to make its DSL access multiplexers compatible with other vendors' customer premises equipment for symmetrical digital subscriber line services.

Unlike asymmetrical DSL (ADSL), which has spawned the Universal ADSL Working Group to address interoperability issues and standards, SDSL has not been targeted by vendors for interoperability development.

The standardized nature of SDSL had led many vendors to not worry about their equipment working with other vendors' products, said Richard Sekar, Copper Mountain's product marketing director. SDSL uses 2B1Q line coding, the same used for ISDN and T-1 transmission, he said.

"SDSL is completely compatible [with existing public network infrastructure]," Sekar said. "It's a proven technology. That's why a lot of people didn't pay attention [to interoperability]. They thought it would be OK."

But differences in the ways vendors move packets over the standard line means that some equipment will not function with other makes.

Increasing SDSL deployments by competitive local exchange carriers, which are targeting business customers for their DSL services, highlighted the fact that SDSL interoperability needs to be addressed, said Greg Howard, senior analyst for Infonetics Research.

Until recently, SDSL had been confined to lab tests and pilot deployments, where multivendor environments did not come into play.

"Now that you're seeing CLECs deploying these services, [interoperability] is an issue these vendors have to resolve," Howard said. "It's important to the progression of DSL deployment."

CLEC requests prompted Copper Mountain to address interoperability, Sekar said. The company has achieved full interoperability with Netopia Inc. and another vendor yet to be announced. The success of those efforts prompted Copper Mountain to establish a program in which CPE vendors could bring their equipment for testing with Copper Mountain DSLAMs.

The first phase is ensuring that equipment works properly within the standard SDSL parameters, Sekar said. A second phase allows CPE vendors to take advantage of Copper Mountain DSLAM features that allow variable line rates up to 1.5 Mb/s and service over longer line spans.

"We're not trying to create new standards," Sekar said. "The bottom line is that service providers get a wide range of CPE options, and end users can benefit in terms of cost."

Howard agreed. "If the vendors have interoperability, it becomes more convenient for service providers and end users to choose based on price and feature sets," he said.

Michael Malaga, president and CEO of San Francisco-based CLEC NorthPoint Communications, said SDSL is critical to his company's business plan because it is the focal point of its DSL service offering.

"There are myriad varieties of ADSL, but there's not one that best suits the business customers that we desire," Malaga said. "That doesn't necessarily mean we won't offer ADSL, but we adopted SDSL to appeal to business customers."

NorthPoint is lending its support to the Copper Mountain initiative because it is relying on Copper Mountain DSLAMs. But the more CPE brands that will work with NorthPoint's DSLAMs, the better NorthPoint will be able to serve a wide range of customers, Malaga said.

Copper Mountain will not initiate efforts for similar programs to make its CPE interoperable with other vendors' DSLAMs, but it is open to offers from other DSLAM vendors, Sekar said.

ADC Kentrox (CPE vendor)

Cayman Systems (CPE vendor)

Escalate Networks (CPE vendor)

Fastcomm Communications Corp. (CPE vendor)

Flowpoint Corp. (CPE vendor)

FreeGate Corp. (CPE vendor)

Netopia Inc. (CPE vendor)

NorthPoint Communications Inc. (data CLEC)

Ramp Networks (CPE vendor)

Rockwell Semiconductor Systems (chip maker)

Whistle Communications Corp. (CPE vendor)

Source: Copper Mountain Networks

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