Last week, Uunet, one of the UK's largest service providers, revealed that it is considering cancelling its corporate ADSL services due to prohibitive pricing by BT (see Network News, 2 February). However, experts are warning that this is by no means the last skeleton to be found in the cupboard of the broadband technology hailed as a panacea for all things bad in corporate Internet access.
While pricing of the service remains an obstruction to its popularity, experts have warned that ADSL also harbours some technical problems. According to Raghu Bathina, vice president of broadband networking at Ramp Networks, one of the main problems associated with ADSL technology is the challenge of integrating new equipment into corporate infrastructures.
"As feeds like these are fed into the back-end network and companies offerspeeds above 1.5Mbps, it creates a strain," he said. "It's not surprising that they will encounter technical glitches in the short term."
Taking it to the limit
Tim Johnson, analyst at research consultant Ovum, said another problem is the quality of existing copper cabling as DSL pushes copper networks to the limit by operating at frequencies above voice channels. "The wiring was built for voice, not data, so it isn't built to carry high frequencies. If you have copper wires in the same bundle, carrying high frequencies such as those associated with DSL, they can interfere with each other," he said.
Johnson added that another big issue for DSL implementers is coverage. Many companies can't get a DSL service, partly because of the distance they have to cover. The longer the copper wire that connects the local access point to the customer's site, the less reliable the link.
The problem is exacerbated by the way cabling is set up in telephone networks. Generally, a network will feed a long wire from an exchange into a certain area. Instead of cutting into the wire to provide access to the customer's site, telcos will connect to the area using a technique called bridge tapping. "That is normal wiring practice, but it's not good for DSL," Johnson said.
Another problem - identified in the US where DSL technology is more pervasive - is that many telephone connections use a digital loop carrier (DLC) device that increases the number of channels in the local route. This works by converting analog signals to digital before multiplexing them over the same cable pair.
Unfortunately, said Johnson, it is difficult to get DSL to run through the DLC. Instead, a Lan device must be inserted into the DLC. All of these problems limit coverage.
The European connection
To make things even more complex, Europe's advanced communications networks pose even greater problems with DLC technology. In the UK, optical fibre has penetrated much further into the network, but most variations of DSL are only designed to work over copper. Therefore, a DSL access multiplexor (DSLAM) is required for it to work.
Johnson said: "The pressing things are size and power supply. DLCs are just boxes, yet you have to squeeze the laptop-sized DSLAMs into there somewhere."
A further problem is posed by European telecoms regulators. Richard Feasey, director of regulatory affairs at MCI Worldcom International, blamed the lack of regulatory frameworks for poor DSL coverage. He is currently talking to BTand other companies about buying either raw copper access, or a managed servicewhere BT retains ownership of the DSL equipment but MCI Worldcom resells services.
For companies that cannot get DSL access in the near future, there are alternatives. Technically, cable modem technology could be used to provide high-speed Internet connectivity to a business, although this hasn't yet proven popular.
The pick of the crop
Jeff Walker, director of product management for Motorola's multimedia group, said cable companies are eager to cherry-pick customers from the business environment.
Russell Haggar, of product development and business innovation consultancy Scientific Generi, believes that the issue for cable users is that often, multiple customers share a single cable drop.
As more and more companies begin to use the service in a neighbourhood, bandwidth levels will fall. Businesses will be loathe to use a service thatdeteriorates over time, and for which corporate-standard service levelagreements are difficult to obtain, he said.
One of the biggest problems for cable operators is a lack of understanding ofboth digital services and the service levels that are required of them by theconsumer market, said Haggar. They also have an inferior understanding of howto deliver data services and charge for them, he warned.
Citing a personal experience with one cable company, which had data capability but didn't have the necessary billing system, he said: "Telephone companies have been delivering data for years. They potentially have a better relationship with the customer and they know more about data."
The other option for companies is satellite technology, which is easy to install but suffers from high latency levels and normally very high charges.
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