Telecom nails its colours to ATM and ADSL

The mists are clearing from Telecom's broadband strategy to reveal ATM and ADSL as its twin flagships. Telecom's broadband product manager Phil Turnbull yesterday outlined outlined Telecom's thinking on the broadband infrastructure for which it is quietly gathering resource consents.

The mists are clearing from Telecom's broadband strategy to reveal ATM and ADSL as its twin flagships.

Telecom's broadband product manager Phil Turnbull yesterday outlined outlined Telecom's thinking on the broadband infrastructure for which it is quietly gathering resource consents.

Turnbull says Telecom has looked at the whole range of "XDSL" technologies, which use special exchange switches to deliver high bandwidth residential services over existing copper circuits, and decided that ADSL (Asymmetrical Digital Subscriber Line) "is the one which fits our niche and provides the best medium-term solution."

An ADSL switch can drive copper to a distance of 3-4km and is fairly tolerant, making it a relatively easy solution to apply to Telecom's existing network, but Turnbull says the long-term answer may be VDSL (Very high speed Digital Subscriber Line). VDSL will work only over relatively short stretches of copper, and is less tolerant of line quality.

VDSL's lab performance has hit downstream rates of up to 52Mbits/s, says Turnbull "which is amazing when you consider how long copper has been around."

This compares with downstream rates of 2Mbit/s and 200Kbit/s achieved by Telecom in its ADSL-ATM trials.

"We probably could have done a bit better than that, but our aim was more to see what happens to Webservers when you pull information off them very quickly," says Turnbull. "And the results were very interesting. We found that using, say, a Netscape browser with a Netscape server tended to work better than mixing servers and clients."

ATM itself may one day incorporate frame realy and even PSTN-type voice services into a single network, says Turnbull, but in the medium term its promise lies in high-bandwidth applications such as telemedicine, in which Telecom is running a trial with South Auckland Health and Middlemore Hospital.

Telecom's Opera ATM trial is also being used to develop client-side "telepresence" applications in Java. The applications, originally developed at the University of Surrey are being used to provide virtual lecture facilities between the Palmerston North and Albany campuses of Massey University.

But the business community will first see "the same generic set of services with which ATM has been launched in other parts of the world," says Turnbull. These are LAN bridging (providing high-speed circuits to extend the coporate LAN); ATM linking or cell relay (for customers using ATM locally); ATM to frame relay internetworking; and 2M emulation.

Apart from increased access speed, the benefits to customers of ATM services will centre around flexibility, says Turnbull.

"ATM will allow us to provide more flexible, scalable services, and to negotiate more customised level of service agreements," says Turnbull. "We'll also be able to offer more flexible billing - by bandwidth, usage, time or any combination of the three."

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