Monday, February 11, 2008

Traffic Shaping: BitTorrent and P2PTV

Lately there's been a lot of press about Internet Service Provider (ISP) traffic shaping with much of the discussion focused on BitTorrent based applications. Let's take a look at BitTorrent and how it is being used to distribute large files on the Internet. I'll use content from a Free Press piece published last fall to describe the steps involved for a user to start using BitTorrent:

Step 1: A user first downloads a program known as a BitTorrent client. Popular bit torrent clients (there are many) include uTorrent, BitComet and ABC. Once a BitTorrent client is installed the user can then share and download files.

Step 2
: Once the client is installed, users can then search for interesting content. The user then finds a “torrent,” which is a miniscule file that serves to point a user’s computer in the direction of that file’s location. The torrent contains data that identify the file or files to be downloaded and a tracker notifying the computer coordinating such file distribution (many also utilize a trackerless system in which each connected computer acts as a tracker) that another user is interested in obtaining the file. All the rest of the BitTorrent users currently downloading or possessing the file (through keeping their application open, known as “seeding”) help transmit small portions of the overall file to the requesting user.

Step 3
: As the user begins to acquire portions of the overall file, their computer redistributes the content to other users also requesting the file. The BitTorrent protocol differs from traditional point to point P2P networks where a central server distributes the information to each user, thereby putting all the strain on a single source.

Since it was released in 2001, BitTorrent has been the focus of some bad press because it can be used to illegally distribute copyrighted content. Things are changing though - BitTorrent applications also allow original content creators to not incur the entire cost of hardware, hosting and bandwidth - potentially providing huge savings to networks selling video content, record companies selling music, companies selling software.

One of my favorite BitTorrent "like" applications is Joost. Joost uses Peer-to-Peer television (P2PTV) to legally distribute content. We've all watched video streams (YouTube is a good example) where the video is streamed off a server - nice but relatively low resolution. Joost (requires an install of a separate application and does not run in a web browser) uses P2PTV to deliver high resolution video by having each client running it propagate the stream to more downstream clients. This moves the distribution costs from the channel owner to the user.

Later this week I'll write about technology that can be used to shape this kind of traffic on a network.

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