BitTorrent at War With VoIP? Hardly

The Internet is close to a meltdown, according to The Register. The culprit, according to author Richard Bennett, is the popular BitTorrent client uTorrent, which introduced a new type of file transfer with its most recent alpha version. BitTorrent clients have long been using the TCP protocol to facilitate file transfers, but now uTorrent is moving to UDP, a protocol that is very popular for streaming media, VoIP and other real-time transfers. This will essentially lead to torrents eating up all of the bandwidth available for VoIP, according to Bennett, who calls uTorrent’s UDP transfers a “net-killing feature.”

Of course, the same argument was made when UDP-based VoIP connections and video streams became popular — and the Internet hasn’t ceased to exist. The truth is that uTorrent’s UDP implementation could actually be a step toward alleviating congestion problems. Bennett, however, decided to ignore this and instead serve up nothing more than a thinly veiled rant against net neutrality.

Bennett’s piece is based on a belief that UDP traffic is “aggressive” and uncontrollable, whereas TCP is the nice and proper protocol that can be easily managed. This notion ignores the basic fact that P2P developers, in order to make the protocol work at all, need to implement TCP-like functionalities on top of UDP, one of which includes congestion control. You simply can’t operate a P2P client that eats up all of its users’ bandwidth, much less build a successful business model on top of it.

BitTorrent Inc. has been working on establishing itself as a CDN solutions provider, offering media companies the ability to tap into its vast user base to deliver video and other huge files. Of course, this only works if end users are actually willing to provide some part of their upload bandwidth, and they are only willing to do so if file transfers don’t stop them from doing other things, like playing online games or making VoIP calls.

BitTorrent has traditionally entrusted its users with figuring out how to balance their network load, meaning that users had to manually limit their client’s maximum upload and download rate in case they encountered choppy Skype connections or similar problems.

uTorrent’s new implementation wants to automate this process by regulating its UDP traffic in relationship to ongoing TCP transfers. The company has tested its congestion control in recent months, and the first results seem encouraging, as a quote from a report (PDF) that the company recently shared with the IETF reveals:

“In one example, (BitTorrent) was used to download and seed game updates while an online multiplayer game was being played. With TCP used for transport the way it is usually used in BitTorrent, ping times shot up to 2000 milliseconds and beyond and stayed there while seeding. With the novel congestion control, ping times were in the 50-100 millisecond range, while the upload rate remained essentially unchanged.”

For now, we do have to take the company’s word for it that this actually works. uTorrent is not open source, and the client’s UDP file transfer protocol hasn’t been publicly specified, either. BitTorrent Inc. V-P Simon Morris has declared in a public response to the Register article that his company is working with the IETF to find “solutions that can be standardized and broadly adopted in due course.” In fact, BitTorrent engineer Stanislav Shalunov is co-chairing an IETF working group for this very purpose.

So why did Bennett chose to ignore all of this? Because a little scaremongering can go a long way to make the case for an ISP-based network management clampdown on P2P traffic. The only way to prevent the coming Internet meltdown, he contends, is to filter out uTorrent’s UDP transfers on the ISP level, and the only way to get this done is do away with net neutrality. Right — because if there’s one thing that we’ve learned from the financial sector, it’s that meltdowns are best prevented by doing away with regulation.


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