The BBC has raised concerns after it learned that BT's Total Broadband traffic management platform was being used to throttle the speed at which customers view web based video sites, such as its own iPlayer service and YouTube. Customers that take BT's cheaper Option 1 deal will find their speeds to streaming video sites reduced to less than 1Mbps between the hours of 1700 and midnight.

Typically many such sites automatically base their video quality on a customer’s connection speed, hence reducing this can also have a serious impact on visual clarity (less bandwidth, less quality). The BBC iPlayer works at three different speeds - 500Kbps (0.5Mbps), 800Kbps (0.8Mbps), and 1.5Mbps. iPlayer's high definition service also requires 3.2Mbps; close to the national average speed.


BT's use of traffic management is nothing new and its own website confirms that speeds to all video streaming services will be limited to "896Kbps on our Option 1 product, during peak times only". Still, some users appear to find the service so poor at such speeds as to be virtually unusable.

Interesting the BBC has studied data from related BT connections and found that speeds were actually being reduced down to around 700Kbps, something that BT denies. Typically speed testing is not an exact science and such a variation from the stated 896Kbps would not be unexpected, albeit depending on the BBC's sample size.

Many UK ISPs use similar methods to restrict traffic to specific services, such as P2P or binary newsgroups, during certain times of the day. This helps to save money by balancing the network in favour of the majority rather than a minority of extremely heavy users. But excessive use of such technology can easily contradict the marketing that many ISPs use to promote their services. Claims like, "we'll offer the best speed available on your line", quickly fall foul of vague Fair Usage Policies.

We have long called for more transparency on this matter and mercifully some ISPs , such as Virgin Media and PlusNet , do now put more effort into explaining precisely how and when any restrictions are applied. Sadly many other providers fail to do this. In the case of BT’s service it should also be recognised that Option 1 is a budget price package and not well designed for video viewing.