DSL is one big mess

By Tim Greene
Network World, 6/1/98

It was bad enough when we had two types of 56K bit/sec modems, but how would you like to wade through over 10 flavors of digital subscriber line (DSL) technology, none of which is compatible with any of the others?

That is exactly what carriers face when they try to bring DSL services to market, slowing down and complicating deployment - and confusing the heck out of anxious customers.

DSL is one of today's most promising wide-area access technologies, carrying broadband data over regular telephone wires. It has the potential to make fast and cheap Internet access common, and provide inexpensive and efficient high-speed remote access to corporate networks.

Users naturally are excited about moving to DSL, but at the same time, their heads are spinning from trying to sort out all the different varieties.

"I still get confused with ADSL, SDSL, xDSL," said Keith Waldorf, chief information officer of Employers Medical Network, Inc. in San Jose, Calif., who has actually bought a 1.5M bit/sec DSL connection.

Waldorf spent a lot of time researching the technology before buying the service from Northpoint Communications, Inc., but last week was still surprised to learn about even more DSL flavors.

Waldorf is concerned that the hardware he had to buy to support the service may be useless if he switches to another carrier that uses a different flavor of DSL to support its services. "I said, 'OK then, who am I compatible with?' I'm in the same boat as everybody else. I don't know what the standards will be."

Help on the way?

A group of industry heavyweights has gotten together to solve the multiple-flavor problem - by coming up with yet another flavor. The Universal ADSL Working Group (UAWG) is pushing to standardize a lightweight customer DSL modem that can talk to anybody's service provider modem - as long as the provider's modem also meets the standard.

The UAWG includes the major European and U.S. regional phone companies, as well as Microsoft Corp.,

Intel Corp., Compaq Computer Corp. and most DSL hardware makers.

The UAWG collaboration is all well and good, but some members of the group seem at odds with the goal. Nortel, Paradyne Corp. and Rockwell Semiconductor Systems endorse the goal of universal DSL, but also produce technologies that are not fully in sync with the previously proposed UAWG guidelines.

In addition, there is no guarantee from some UAWG members that they will endorse the official standard, which will be called G.Lite, according to Ken Krechmer, who sits on the International Telecommunication Union (ITU) committee considering G.Lite. The UAWG is providing input into the ITU standards process.

The wealth of DSL flavors and dearth of standards has made phone companies cautious about rolling out DSL services. In the meantime, new competitive local carriers have stepped up with aggressive DSL rollouts, but the carriers have to work around the limitations.

For example, Covad Communications, Inc. in San Francisco offers DSL at speeds from 144K bit/sec to 1.5M bit/sec. But to do that the

carrier uses two different DSLs - ISDN-based DSL and rate adaptive DSL.

Also, to make the provisioning of its services simpler, Covad tosses out the ability DSL has to carry a separate voice channel on the same wires.

Because DSL is costly and complex to offer as a service, it probably won't become widely available until after 2000, according to Neil Spicher, president of Twenty-first Century Consultants in Sacramento, Calif., which advises on DSL services.

Providers that do offer DSL will do so only where they can draw a high number of users in a small area, he said.