Dressed-down DSL: Multiple virtual line technology offers a low-power DSL alternative

There's a new kid on the block in broadband land. Multiple virtual line technology, pioneered by Paradyne, promises service providers a quick and easy way to offer multiple services over phone lines. The scheme sounds a lot like digital subscriber line, but the vendor says its low power, 768 kb/s symmetrical data rate and bandwidth utilization technique make it something special.

"Instead of downsizing DSL or stretching analog modems to their limit, what was needed was something completely different," said Ron Stein, vice president of marketing at Paradyne.

The vendor has announced one-port multiple virtual line modem cards for its 8600 and 8800 Hotwire DSL access multiplexers (DLSAMs) and stand-alone end user modems, which feature one Ethernet and one RJ-11 port.

At its most basic level, the technology is a variation of DSL. It works over twisted copper pair, requires a one-to-one modem connection and supports voice and data transmissions simultaneously. But multiple virtual line technology is unique in several ways. For one, it works over untwisted copper pair. That eliminates installation problems at customer locations with unpredictable wiring configurations, and it helps service providers reach a wider scope of subscribers.

Multiple virtual line also emits a low power level-around 1.5 watts per modem card, according to Paradyne. The low power also enables the technology to be deployed in digital loop carriers and to coexist with neighboring technologies in carriers' copper bundles such as T-1 and analog voice services. It also lets multiple virtual line modems operate at up to 24,000 feet from the central office and eliminates the need for a POTS splitter. Paradyne says it will ramp down power to 0.5 watts in later releases of the technology.

Another plus for multiple virtual line is that it's based on off-the-shelf digital signal processors.

That promises to keep the product prices low, enable software upgrades for new features and offer high port densities within the central office. A four-port multiple virtualline modem card will be available by the end of the year.

According to the vendor, several PCs, each equipped with an multiple virtual line modem, can share the bandwidth to access the Internet, transfer files and even videoconference (see figure). However, throughput decreases with each PC using the line.

What are the other downsides? For starters, the technology is being offered only by Paradyne, so to take advantage of multiple virtual line, service providers must use Paradyne DSLAMs in their networks.

What's more, no standards for the technology have been established yet.

Paradyne is targeting service providers such as U S West to market the technology to their customers at $299 per line. Thorn Communications, a New-York-based Internet service provider, is planning to offer multiple virtual line service in multi-tenant setups at rates of $65 to $100 a month and a one-time installation fee.

BAY NABS PARADYNE DSL Major networking vendor Bay Networks has entered a reseller agreement with Paradyne Networks to provide its ISP and CLEC customers with Paradyne's DSL equipment. The vendor will offer rate adaptive DSL, high bit-rate DSL and symmetrical DSL services. Bay Networks will develop its own proprietary DSL product in the future.

HDSL AGREEMENT HDSL equipment manufacturer PairGain Technologies announced an OEM agreement with Vina Technology at ComNet '98. PairGain will include Vina's T-1 Integrator into its own equipment. In turn, Vina will incorporate PairGain's HDSL technology into its products. Vina is an access equipment provider.