Bandwidth and QoS: Much ado about something

by on April 24, 2009 · 3 comments

The supposed top finding of a new report commissioned by the British telecom regulator Ofcom is that we won’t need any QoS (quality of service) or traffic management to accommodate next generation video services, which are driving Internet traffic at consistently high annual growth rates of between 50% and 60%. TelecomTV One headlined, “Much ado about nothing: Internet CAN take video strain says UK study.”

But the content of the Analysys Mason (AM) study, entitled “Delivering High Quality Video Services Online,” does not support either (1) the media headline — “Much ado about nothing,” which implies next generation services and brisk traffic growth don’t require much in the way of new technology or new investment to accommodate them — or (2) its own “finding” that QoS and traffic management aren’t needed to deliver these next generation content and services.

For example, AM acknowledges in one of its five key findings in the Executive Summary:

innovative business models might be limited by regulation: if the ability to develop and deploy novel approaches was limited by new regulation, this might limit the potential for growth in online video services.

In fact, the very first key finding says:

A delay in the migration to [British Telecom's next generation] 21CN-based bitstream products may have a negative impact on service providers that use current bitstream products, as growth in consumption of video services could be held back due to the prohibitive costs of backhaul capacity to support them on the legacy core network. We believe that the timely migration to 21CN will be important in enabling significant take-up of online video services at prices that are reasonable for consumers.

So very large investments in new technologies and platforms are needed, and new regulations that discourage this investment could delay crucial innovations on the edge. Sounds like much ado about something, something very big.

On the QoS question, AM appears to make a number of important oversights/omissions. I have only done a quick reading, but upon first examination:

– AM considers only downstream non-interactive video, such as download-and-cache, streamed medium quality services like YouTube, and high-end video like IPTV.

– AM does not consider two-way interactive real-time video, such as obvious applications like video-calling, video-conferencing, and Telepresence, or less obvious but still important future applications like 3D gaming, Cinema 2.0 interactive movies, high-resolution interactive virtual worlds, and a whole host of cloud-based services we cannot even imagine.

– These real-time interactive video applications and services impose more severe restrictions on bandwidth, latency, and jitter than static downstream video applications.

– The report does not appear to address the importance that QoS will play in the wireless/mobile realm. In the necessarily more bandwidth constrained environment of wireless, QoS is like to play a very important role in delivering video-calling, gaming, and other interactive services.

– Throughout the report, AM also acknowledges the key role content delivery networks (CDNs) play in delivery of video and other content. CDNs are NOT a bandwidth solution. They are a caching solution that improves “QoS” through hop-reduction and latency-reduction. They are in fact a bandwidth-saving device, and also a topological mechanism to cope with the, alas, finite speed of light.

– The mere fact AM spends so much time on CDNs undermines its own headline saying we can accommodate all new video traffic with more bandwidth.

– Bandwidth is a very big part of the equation. But so are CDNs, QoS, and a range of other technological, topological, and architectural strategies.

– I also have not yet found in the paper a detailed or persuasive rationale for the “finding” that bandwidth is ALWAYS a better solution than QoS. Bandwidth is indeed a good substitute for switching and/or QoS, but not always. And it is not always the most economically efficient solution.

I may revise and extend these observations, but upon first glance, the headlines don’t reflect the substance, and in a few cases, like its analysis of QoS, real-world substance doesn’t support the findings.

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