LinuxSA Mailing list archives

  From: Alan Kennington <akenning@topology.org>
  To  : LinuxSA <linuxsa@linuxsa.org.au>
  Date: Tue, 12 Jun 2001 02:14:09 +0930

Re: [OT] Telstra ADSL 'Unlimited' Introduces Download Limit

On Tue, Jun 12, 2001 at 01:23:42AM +0930, David Lloyd wrote:
> 
> [....] Putting it bluntly, I absolutely fail to
> understand why people expect to get unlimited stupid downloads from an
> ISP for no price.
> 


David,

I'd like to add some background to this.
Over the last 10-15 years, people in the protocol
design area have often noted that there are two kinds of
people contributing:

1.	Telco people, who think that all networks are
	connection-oriented, with fixed bit-rate links,
	or they wish that they were.
2.	Computer people, who think that all networks are
	just big LANs, or wish that they were.

The clash of cultures has been constant over the last decade
or two. The Internet combines two incompatible world views.

Group 2 probably describes most people with a strong computer background.
Since they are used to fast computers connected to
free, infinite-bitrate LANs in their office, they see no reason
why this should not be so on the Internet, which they consider to
be an extension of the LAN.

Group 1 cannot understand why they can't get a fixed bit-rate
connection which is reliable.
The Internet protocols were designed by group 2.
The ATM protocol was designed originally by group 1, and then
group 2 took over, but it never recovered.
Modem protocols were invented by group 2.
And so forth.

The problem is that neither group is right.
To really understand how the Internet work, it is necessary to
think as both groups simultaneously.


The trouble is that there's been too much macho talk by
manufacturers about the new world of terabits/sec fibre links
and all that stuff.
User have to imagine that the Internet is a _shared_ network,
and the network operators are just like operators of the
village well. If they give infinite free water to everyone,
the well will soon be dry, and they won't have any profit left
over to dig a _new_ well.

In fact, the mathematics and economics of internet access is
not very dissimilar to how the village well industry works.

Another way to to think of it is this:
Internet access is like a hot water heater.
If everyone uses it too much, it will go cold.
You have to leave it idle for a while to let it warm up again.

And token buckets are mathematically very similar to
hot water heaters.

Cheers,
Alan Kennington.

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