You are assuming the absence of any of the following optimizations: 1. Multicast 2. Overlay networks using P2P services (get parts of your stream from some of your neighbors).
These are not entirely safe assumptions. Owen On Dec 2, 2010, at 12:21 PM, Leo Bicknell wrote: > > 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-on-what-it-costs-netflixs-to-stream-movies.html > > 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-sunday-night-football-dancing-with-the-stars-finale-two-and-a-half-men-ncis-top-week-10-viewing/73784 > > 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 - bickn...@ufp.org - CCIE 3440 > PGP keys at http://www.ufp.org/~bicknell/