Network end users to pull down 2 gigabytes a day, continuously?

Sean Donelan sean at
Mon Jan 8 07:34:01 UTC 2007

On Sun, 7 Jan 2007, Joe Abley wrote:
> Setting aside the issue of what particular ISPs today have to pay, the real 
> cost of sending data, best-effort over an existing network which has spare 
> capacity and which is already supported and managed is surely zero.

As long as the additional traffic doesn't exceed the existing capacity.

But what happens when 5% of the paying subscribers use 95% of the existing 
capacity, and then the other 95% of the subscribers complain about poor 
performance?  What is the real cost to the ISP needing to upgrade the
network to handle the additional traffic being generated by 5% of the
subscribers when there isn't "spare" capacity?

> If I acquire content while I'm sleeping, during a low dip in my ISP's usage 
> profile, the chances good that are nobody incurs more costs that month than 
> if I had decided not to acquire it. (For example, you might imagine an RSS 
> feed with BitTorrent enclosures, which requires no human presence to trigger 
> the downloads.)

The reason why many universities buy rate-shaping devices is dorm users 
don't restrain their application usage to only off-peak hours, which may 
or may not be related to sleeping hours.  If peer-to-peer applications 
restrained their network usage during periods of peak network usage so 
it didn't result in complaints from other users, it would probably 
have a better reputation.

> If I acquire content the same time as many other people, since what I'm 
> watching is some coordinated, streaming event, then it seems far more likely 
> that the popularity of the content will lead to network congestion, or push 
> up a peak on an interface somewhere which will lead to a requirement for a 
> circuit upgrade, or affect a 95%ile transit cost, or something.

Depends on when and where the replication of the content is taking place.

Broadcasting is a very efficient way to distribute the same content 
to large numbers of people, even when some people may watch it later.  You 
can broadcast either streaming or file downloads.  You can also unicast 
either streaming or file downloads. Unicast tends to be less efficient 
to distribute the same content to large numbers of people.  Then there is 
lots of events in the middle.  Some content is only of interest to a some 

Streaming vs download and broadcast vs unicast.  There are lots of 
combinations.  One way is not necessarily the best way for every
situation.  Sometimes store-and-forward e-mail is useful, other times
instant messenger communications is useful.  Things may change over 
time.  For example, USENET has mostly stopped being a widely flooded 
through every ISP and large institution, and is now accessed on demand by 
users from a few large aggregators.

Distribution methods aren't mutually exclusive.

> If asynchronous delivery of content is as free as I think it is, and 
> synchronous delivery of content is as expensive as I suspect it might be, it 
> follows that there ought to be more of the former than the latter going on.
> If it turned out that there was several orders of magnitude more content 
> being shifted around the Internet in a "download when you are able; watch 
> later" fashion than there is content being streamed to viewers in real-time I 
> would be thoroughly unsurprised.

If you limit yourself to the Internet, you exclude a lot of content
being shifted around and consumed in the world.  The World Cup or 
Superbowl are still much bigger events than Internet-only events. Broadcast
television shows with even bottom ratings are still more popular than 
most Internet content.  The Internet is good for narrowcasting, but its
still working on mass audience events.

"Asynchronous receivers" are more expensive and usually more complicated
than "synchronous receivers."  Not everyone owns a computer or spends a
several hundred dollars for a DVR.  If you already own a computer, you 
might consider it "free."  But how many people want to buy a computer for 
each television set?  In the USA, Congress debated whether it should
spend $40 per digital receiver so people wouldn't lose their over the 
air broadcasting.

Gadgets that interest 5% of the population versus reaching 95% of the 
population may have different trade-offs.

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