On Jan 10, 2007, at 1:49 AM, Marshall Eubanks wrote:
Dear Valdis;
On Jan 9, 2007, at 10:02 PM, [EMAIL PROTECTED] wrote:
On Tue, 09 Jan 2007 11:29:32 EST, Gian Constantine said:
If you considered my previous posts, you would know I agree
streaming
is scary on a large scale, but unicast streaming is what I
reference.
Multicast streaming is the real solution. Ultimately, a global
multicast network is the only way to deliver these services to a
large market.
Multicast streaming may be a big win when you're only streaming
the top
5 or 10 networks (for some value of 5 or 10). What's the performance
characteristics if you have 300K customers, and at any given time,
10%
are watching something from the "long tail" - what's the
difference between
handling 30K unicast streams, and 30K multicast streams that each
have only
one or at most 2-3 viewers?
This is a very good point. It is very reasonable to expect viewing
choices to follow
a Pareto distribution (such as Zipf's law or the 80-20 rule). That
plus some reasonable
economic assumptions make 30K commercial channels not an
unreasonable assumptions in a
few years. But that also implies that it is _not_ realistic to have
"30K multicast streams that each have
only one or at most 2-3 viewers." You may have 30K streams, most
may have only a few viewers, and
still have fairly large savings.
To flesh out your example,
if you have 1 million viewers on your network, and if you assume
30K channels and
the same Pareto distribution as web sites,
- the largest channel has 1.8% of the audience
- 50% of the audience is in the largest 2700 channels
- the least watched channel has ~ 10 simultaneous viewers
- the multicast bandwidth usage would be 3% of the unicast.
These same models IMHO makes cell phone RF multicast not incredibly
compelling. Because there is less
feedback on a multicast RF, the power has to be greater for a
multicast channel, and
in that case the bandwidth (or RF power) savings are small or even
negative, because you only
have maybe 100 people on a cell watching.
s/watching/watching content from your 30K channels/
Regards
Regards
Marshall
