The scale of streaming video on the Internet.

Thu Dec 2 20:28:47 UTC 2010

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 - bicknell at ufp.org - CCIE 3440
>        PGP keys at http://www.ufp.org/~bicknell/