Friday, December 26, 2008

Upgrading TCP for the Heavy User

Bob Briscoe from BT wrote an article that appeared in the December 2008 IEEE Spectrum that discusses proposed changes to TCP that would help the Internet cope better with so-called bandwidth hogs. It basically does this by providing a mechanism that allows network routers to discard packets from the heavy users before discarding packets from casual users.

Heavy users will declare their packets to be eligible for discard and a feedback mechanism will be created that will inform core routers of congestion that is occurring in the network so that they can start discarding packets.

This approach should provide better performance to the casual user than they experience today without significantly degrading performance for the heavy user.

You can get more details from Briscoe's web site.

It looks to me that this is a much better approach than the limits being proposed by carriers today. It also seems to resolve the Net Neutrality argument by redefining what fairness means and equalizing the performance of the network to a broad set of users rather than equalizing access to bandwidth.

I question how much these techniques will help in an IP network dominated by TV traffic. TV traffic wants to use a lot of bandwidth and have a high QoS at the same time. An HDTV viewer will not like it if discarding packets from his or her video stream causes visual or audio defects.

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