Traffic controls on info-highway

Oxford Brookes and British Telecom have quelled fears that an unchartered route on the information superhighway could become jammed and unmanageable with the development of a new regulating device.

The single communications network, which carries voice, video, graphics and data, is now open to "casual" customers who have not reserved a line. But there are problems in assigning space to users of this so-called Available Bit Rate service and handling the wide variety of "traffic" on the superhighway with minimum disruption.

The network must carry traffic with a variety of requirements, such as computer information which travels in bursts and can be transmitted slowly but requires a high level of reliability.

An answer has been found through the collaborative work of Avril Smith, a researcher in the school of computing and mathematical sciences at Oxford Brookes University, and BT technicians.

They have patented a device called the Dynamic Bandwidth Controller to control flow on the ABR service by assigning appropriate space to customers who "drop in" on the superhighway.

Dr Smith likens the role of the new device to a hotel receptionist. "It reserves space for an agreed time, allocates free space to customers arriving on spec, and in times of overbooking, prioritises the use of available space to minimise disruption," she said.

It is likely to prove popular with BT customers, enabling companies to use the full "bandwidth" on the Available Bit Rate service and provide a reasonably priced, pay-as-you-use system rather than a designated line per customer.

Trials on the new device are planned to begin later this year.