Access wars

Reality Check  By Thomas Nolle, Network World, 02/20/08

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Last year, the Associated Press reported that a test of BitTorrent peer-to-peer traffic on Comcast’s network showed that the cable giant was somehow interfering with P2P flow. This year, there’s a story that AT&T and Verizon have at least looked at restraining P2P. Whatever the truth in these rumors, the industry is surely poised on the edge of the most important debate in the history of the Internet. Sadly, like most political debates, this technical one probably won’t expose too many facts.

P2P is not the problem that Internet access providers face, it’s a symptom of a larger problem, which is how we can fund the kind of public data and content services we all expect in the future. Despite the public expectation that the Internet is going to keep getting faster and more powerful, the future of public networking is a bit murky, and the industry itself is the root cause.

Data traffic of any sort isn’t a steady stream, it’s a series of bursts, and most consumer traffic bursts flow mostly out of the network to the customer and not the other way around. Consumer data access has long taken advantage of this, creating more capacity downstream than upstream. DSL and cable services today are asymmetrical in this sense, typically offering five or more times the capacity in downstream. DSL and cable services also expect that customers won’t be using all of the capacity of their access connection all of the time. Cable customers share bandwidth with all the others on the cable span, and DSL customers share capacity with others on their fiber remote. These sharing assumptions combine to create affordable broadband access by spreading the cost of fiber bandwidth across many homes. The result is that a homeowner can get anywhere from 6M to 30Mbps of bandwidth for less than one-tenth the cost per bit of dedicated, symmetrical, full-time broadband services of the type corporations buy.

The problem with sharing is that not everybody shares nice. Any user who operates outside the framework of typical access that operators have used to design their networks will put the design at risk, and with it the quality of service that users overall can expect. Five years ago, I dropped cable modem data services because some users on my span were serving data in high volume, and so congesting the uplink that service was impacted for everyone — including me. The reason that all broadband operators have usage agreements in their terms of service is that some usage patterns cannot be sustained without either reducing service quality for others or invalidating the economic assumptions of the network. The cable networks, which share capacity to a greater degree than most of the telcos do, are especially vulnerable to P2P, so it’s not surprising the problem appeared here first.

Nolle is president of  CIMI Corp., a technology assessment firm in Voorhees, N.J. He can be reached at (609) 753-0004 or via e-mail.

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