Hidden in the Comcast and Level 3 press release war are some facinating details about the scale of streaming video. In http://blog.comcast.com/2010/11/comcasts-letter-to-fcc-on-level-3.html, Comcast suggest that "demanded 27 to 30 new interconnection ports". I have to make a few assumptions, all of which I think are quite reasonable, but I want to lay them out: - "ports" means 10 Gigabit ports. 1GE's seems too small, 100GE's seems too large. I suppose there is a small chance they were thinking OC-48 (2.5Gbps) ports, but those seem to be falling out of favor for cost. - They were provisioning for double the anticipated traffic. That is, if there was 10G of traffic total they would ask for 20G of ports. This both provides room for growth, and the fact that you can't perfectly balance traffic over that many ports. - That substantially all of that new traffic was for Netflix, or more accurately "streaming video" from their CDN. Thus in round numbers they were asking for 300Gbps of additional capacity across the US, to move around 150Gbps of actual traffic. But how many video streams is 150Gbps? Google found me this article: http://blog.streamingmedia.com/the_business_of_online_vi/2009/03/estimates-o... It suggests that low-def is 2000Kbps, and high def is 3200Kbps. If we do the math, that suggests the 150Gbps could support 75,000 low def streams, or 46,875 high def streams. Let me round to 50,000 users, for some mix of streams. Comcast has around ~15 million high speed Internet subscribers (based on year old data, I'm sure it is higher), which means at peak usage around 0.3% of all Comcast high speed users would be watching. That's an interesting number, but let's run back the other way. Consider what happens if folks cut the cord, and watch Internet only TV. I went and found some TV ratings: http://tvbythenumbers.zap2it.com/2010/11/30/tv-ratings-broadcast-top-25-sund... Sunday Night Football at the top last week, with 7.1% of US homes watching. That's over 23 times as many folks watching as the 0.3% in our previous math! Ok, 23 times 150Gbps. 3.45Tb/s. Yowzer. That's a lot of data. 345 10GE ports for a SINGLE TV show. But that's 7.1% of homes, so scale up to 100% of homes and you get 48Tb/sec, that's right 4830 simultaneous 10GE's if all of Comcast's existing high speed subs dropped cable and watched the same shows over the Internet. I think we all know that streaming video is large. Putting the real numbers to it shows the real engineering challenges on both sides, generating and sinking the content, and why comapnies are fighting so much over it. -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/