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The need for Internet data caps

A few days ago my friend Greg (also known as @etherealmind) wrote an interesting tweet (probably prompted by the change in AT&T data plans):

If a data cap doesn't affect 97% of users, why bother implementing it at all? Surely the 3% can be that significant?

A few of us immediately responded that the 3% could represent 80 (my guess) to 97% (@icemarkom) of the traffic. As I’m tracking my home Internet connection with MRTG for over a year, I was also able to get some hard facts (although the sample size is admittedly very small). We’re pretty heavy internet users (no limits on what my teenage kids are doing and I’m mostly working from home), but the average yearly utilization of my 20 Mbps pipe is only 180 Kbps or less than 1% of its capacity (still, over a year, that’s almost 700 GB of data or 350 months of AT&T’s DataPro plan).

The ever-widening gap between the expected average and peak Internet utilization of an average user and the access line speed is one of the topics of my Market Trends in Service Provider Networks webinar.

Now, imagine that someone deploys a “popular” FTP or BitTorrent server on his home PC. With hundreds of concurrent TCP sessions, it’s very easy to reach constant saturation of the 20 Mbps (or 100 Mbps) link. The ratio between my average Internet utilization and his is 1:100 (and, as said above, I’m probably already in the top 5%).

This time I don’t have to repeat my “All-you-can-eat Internet mentality” rant; Steve Foskett wrote two blog posts along a very similar line of thinking: The End of Unlimited Data: The Buffet and The End of Unlimited Data: Who’s Being Subsidized?

Obviously the Service Providers have two ways to handle the resource hogs: charge them or police them (for example, temporarily lowering their access speed). Most of them choose the obvious solution, trying to collect as much easy money as possible. The smart ones try to match their customer expectations by prioritizing in-contract traffic or rate-limiting specific traffic types and even showing how well they’re doing in a real-time graph.


  1. I later refined this thought to the following : Why not attack the 3% and solve the smaller problem, instead of solving the bigger problem and wasting money.

    You have answered that question by pointing out that they can generate extra revenue. I also agree that it very short sighted.


  2. mokum von Amsterdam14 June, 2010 14:30

    All & every user consumes 3% of the time the top 3% of the bandwidth and that will be capped, not just 3% of the total user base.

    Ergo: your peaks will at some given moment in time be reason to cap|discuss your connected activities, or simply charge more.

  3. Service providers are complaining that customers are beginning to actually consume what was advertised and what they have been paying for. In response, ISPs need to either better invest in their infrastructure to support the services they have promised, or advertise more realistic speeds (e.g. 20 Mbps burst with a CIR of only 2 Mbps). It's that simple. Transfer caps are merely an *additional,* unnecessary restriction on what is already a policed service.

  4. Ivan Pepelnjak15 June, 2010 14:11

    Now we're in perfect alignment. Regardless what each of us thinks, offering 20 Mbps (or 100 Mbps) CIR @ current prices is totally unrealistic, but the terms & conditions should have been very obvious from the beginning.


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