[Nanog] ATT VP: Internet to hit capacity by 2010

michael.dillon at bt.com michael.dillon at bt.com
Tue Apr 22 05:33:44 CDT 2008


> > I think you're too high there! MPEG2 SD is around 4-6Mbps, 
> MPEG4 SD is 
> > around 2-4Mbps, MPEG4 HD is anywhere from 8 to 20Mbps, depending on 
> > how much wow factor the broadcaster is trying to give.
> 
> Nope, ATSC is 19 (more accurately 19.28) megabits per second. 

So why would anyone plug an ATSC feed directly into the Internet?
Are there any devices that can play it other than a TV set?
Why wouldn't a video services company transcode it to MPEG4 and
transmit that? 

I can see that some cable/DSL companies might transmit ATSC to
subscribers
but they would also operate local receivers so that the traffic never
touches their core. Rather like what a cable company does today with TV
receivers in their head ends.

All this talk of exafloods seems to ignore the basic economics of
IP networks. No ISP is going to allow subscribers to pull in 8gigs
per day of video stream. And no broadcaster is going to pay for the
bandwidth needed to pump out all those ATSC streams. And nobody is
going to stick IP multicast (and multicast peering) in the core just
to deal with video streams to people who leave their TV on all day
whether
they are at home or not.

At best you will see IP multicast on a city-wide basis in a single
ISP's network. Also note that IP multicast only works for live broadcast
TV. In today's world there isn't much of that except for news.
Everything
else is prerecorded and thus it COULD be transmitted at any time. IP
multicast
does not help you when you have 1000 subscribers all pulling in 1000
unique
streams. In the 1960's it was reasonable to think that you could deliver
the
same video to all consumers because everybody was the same in one big
melting
pot. But that day is long gone.

On the other hand, P2P software could be leveraged to download video
files
during off-peak hours on the network. All it takes is some cooperation
between
P2P software developers and ISPs so that you have P2P clients which can
be told
to lay off during peak hours, or when they want something from the other
side
of a congested peering circuit. Better yet, the ISP's P2P manager could
arrange
for one full copy of that file to get across the congested peering
circuit during
the time period most favorable for that single circuit, then distribute
elsewhere.

--Michael Dillon

As far as I am concerned the killer application for IP multicast is
*NOT* video,
it's market data feeds from NYSE, NASDAQ, CBOT, etc.




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