[Nanog] ATT VP: Internet to hit capacity by 2010
michael.dillon at bt.com
michael.dillon at bt.com
Tue Apr 22 09:41:27 CDT 2008
> > IP multicast does not help you when you have 1000 subscribers
> > all pulling in 1000 unique streams.
> Yes, that's potentially a problem. That doesn't mean that
> multicast can not be leveraged to handle prerecorded
> material, but it does suggest that you could really use a
> TiVo-like device to make best use.
You mean a computer? Like the one that runs file-sharing
clients? Or Squid? Or an NNTP server?
Is video so different from other content? Considering the
volume of video that currently traverses P2P networks I really
don't see that there is any need for an IP multicast solution
except for news feeds and video conferencing.
> What seems more likely is that we'll see an evolution of more
> specialized offerings,
Yes. The overall trend has been to increasingly split the market
into smaller slivers with additional choices being added and older
ones still available. During the shift to digital broadcasting in
the UK, we retained the free-to-air services with more channels
than we had on analog. Satellite continued to grow in diversity and
now there is even a Freesat service coming online. Cable TV is still
there although now it is usually bundled with broadband Internet as
well as telephone service. You can access the Internet over your mobile
phone using GPRS, or 3G and wifi is spreading slowly but surely.
But one thing that does not change is the number of hours in the day.
Every service competes for scarce attention spans, and a more-or-less
fixed portion of people's disposable income. Based on this, I don't
expect to see any really huge changes.
> That may allow some "less popular" channels to come into
YouTube et al.
> I happen to like holding up SciFi as an example,
> because their current operations are significantly different
> than originally conceived, and they're now producing
> significant quantities of their own original material.
The cost to film and to edit video content has dropped
dramatically over the past decade. The SciFi channel is the
tip of a very big iceberg. And what about immigrants? Even
50 years ago, immigrants to the USA joined a bigger melting
pot culture and integrated slowly but surely. Nowadays,
they have cheap phonecalls back home, the same Internet content
as the folks back home, and P2P to get the TV shows and movies
that people are watching back home. How is any US channel-based
system going to handle that diversity and variety?
> There are almost certainly enough fans out
> there that you'd see a small surge in viewership if the
> material was more readily accessible (read that as:
> automatically downloaded to your TiVo).
Is that so different from P2P video? In any case, the Tivo model
is limited to the small amount of content, all commercial, that
they can classify so that Tivo downloads the right stuff. P2P
allows you to do the classification, but it is still automatically
downloaded while you sleep.
> I'm envisioning a scenario where we may find that there are a
> few tens of thousands of PTA meetings each being uploaded
> routinely onto the home PC's of whoever recorded the local
> meeting, and then made available to the small number of
> interested parties who might then watch, where (0<N<20).
Any reason why YouTube can't do this today? Remember the human
element. People don't necessarily study the field of possibilities
and them make the optimal choice. Usually, they just pick what is
familiar as long as it is good enough. Click onto a YouTube video,
then click the pause button, then go cook supper. After you eat,
go back and press the play button. To the end user, this is much
the same experience as P2P, or programming a PVR to record an
interesting program that broadcasts at an awkward time.
> I don't pretend to have the answers
> to this, but I do feel reasonably certain that the success of
> YouTube is not a fluke, and that we're going to see more, not
> less, of this sort of thing.
> > 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.
> You can go compare the relative successes of Yahoo! Finance
> and YouTube.
Actually, Yahoo! Finance is only one single subscriber to these market
data feeds. My company happens to run an IP network supporting global
multicast, which delivers the above market data feeds, and many others,
to over 10,000 customers in over 50 countries. Market data feeds are not
a mass market consumer product but they are a realtime firehose of data
that people want to receive right now and not a microsecond later. It is
not unusual for our sales team to receive RFPs that specify latency
that are faster than the speed of light. The point is that IP multicast
is probably the only way to deliver this data because we cannot afford
additional latency to send packets into a server and back again. I.e. a
type of solution won't work.
It's not only nice to multicast this data, it is mission critical.
People are risking millions of dollars every hour based on the data in
feeds. The way it usually works (pioneered by NYSE I believe) is that
they send two copies of every packet through two separate multicast
trees. If there is too much time differential between the arrival of the
packets then the service puts up a warning flag so that the traders know
is stale. Add a few more milliseconds and it shuts down entirely because
is now entirely useless. When latency is this important, those copies
to multiple subscribers have to be copied in the packet-forwarding
i.e. router supporting IP multicast.
Of course consumer video doesn't have the same strict latency
therefore my opinion that IP multicast is unneeded complexity. Use the
tool for the job.
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