Comcast to begin capping Internet usage in certain markets.

I don't have an issue with congestion control and usage-based pricing (after all, bandwidth is a scarce resource), but I do take issue with the ham-handed way in which it's being done: monthly usage has no real relationship to the availability of the resource.

ISPs have traditionally billed at 95th-percentile utilization (sample the bandwidth-per-second used into bite-sized chunks, throw out the top 5% of samples, and bill at the highest rate left over). This makes intuitive sense.

But bytes-per-month makes no sense at all. 300GB/month is roughly 1Mb/second. I suppose that's a reasonable fair allocation in terms of average circuit utilization, but a customer who used little traffic during peak periods but 25Mb per second during the wee hours would have little impact on overall availability. In other words, such coarse-grained caps do little to equate supply with demand.