BT's new network: A holy grail?

Posted on 11 Mar 2008 at 17:43

BT is responsible for the vast majority of telecoms infrastructure in the UK, and is currently in the midst of one of its biggest upgrades - the 21st Century Network (21CN).

Today's cabling and switches were designed to move voice calls around. Although capable of carrying data, the bubblegum and bailing wire way of creating a network meant it was inefficient - something BT says will change once its £10 billion investment pays off.

The 21CN moves everything onto Internet Protocol (IP), so whether you make a voice call or upload a video it will be running over a single network, whereas the old system is a hotchpotch of 16 legacy networks.

The rollout has already started, but most of the benefits of the network will be enjoyed by the industry rather than customers. The general user will see little change to their services. The one stellar facelift for broadband is that BT will be replacing the existing DSL hardware in exchanges and upgrading it to ADSL2+, an evolutionary DSL technology with a theoretical 24Mb/sec throughput.

The problem is the technology suffers from the same issues as all DSL, most importantly that it degrades over distance from the exchange. According to Australian ISP Internode research, by the time a signal reaches 4km, which isn't uncommon, it can carry only 4Mb/sec.

While the 21CN will save BT around £1 billion a year, the future-proofing in place for home user broadband subscribers has been derided by critics who believe BT (or the government) should have invested in fibre-to-the-home technology, at a cost of around £20 billion. Meanwhile, the way in which ISPs manage traffic on ADSL2+ services is important - experts say bottlenecks that exist today will be exacerbated as higher speeds mean more traffic through the network.

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Author: Stewart Mitchell