The latest benefit of BT's hugely-hyped 21CN communications system has arrived in the form of 'Etherflow,' a way for businesses to hitch their WANs to an Ethernet-based network.

The company is pitching the service as a replacement technology for once-great ATM and Frame Relay connectivity, with speeds ranging from 10Mbits/s to 1Gbits/s from one of an initial 106 access nodes.

By March 2009, the number of access nodes will be extended to over 600 across the U.K., with a further 400 being rolled out by the end of that year. Throughput will also be rolled down to 2Mbit/s, with the ability for customers to buy bandwidth in 1Mbit/s increments.

The official benefits of Etherflow include a range of quality of service packages from standard through premium, depending on the type of application being supported. Customers will also be able to configure the service themselves using a specially-designed portal.

The biggest feature of Etherflow, however, is the ability to provision bandwidth dynamically, using the portal to raise or lower levels as needed. Current bandwidth provisioning is overwhelmingly based on buying set levels, an inflexible approach that can cause some problems for businesses in terms of capacity planning.

"Our customers are demanding faster and cheaper Ethernet services with the performance and functionality to meet all their networked IT services needs," said BT Global Service's CEO, Royston Hoggarth. "We have been providing Ethernet services for more than 17 years, supporting an installed base of more than 33,000 connections," he added.

The company is understood to be planning an international version of Etherflow for some time in 2009.

BT describes pricing as depending on "a number of factors, including the customer's location, choice of bandwidth and traffic class," but the service is bound to undercut older services such as Megastream as the company migrates clients towards its 21CN systems.