nanog mailing list archives

Re: Why do some ISP's have bandwidth quotas?


From: Joe Greco <jgreco () ns sol net>
Date: Fri, 5 Oct 2007 10:58:12 -0500 (CDT)


Now, ISP economics pretty much require that some amount of overcommit
will happen.  However, if you have a 12GB quota, that works out to
around 36 kilobits/sec average.  Assuming the ISP is selling 10Mbps
connections (and bearing in mind that ADSL2 can certainly go more than
that), what that's saying is that the average user can use 1/278th of
their connection.  I would imagine that the overcommit rate is much
higher than that.

I don't think that things should be measured like this. Throughput !=
bandwidth.

No, but it gives some rational way to look at it, as long as we all realize
what we're talking about.  The other ways I've seen it discussed mostly
involve a lot of handwaving.

Technically the user can use the connection to it's maximum theoretical
speed as much as they like, however, if an ISP has a quota set at
12G/month, it just means that the cost is passed along to them when they
exceed it.

And that seems like a bit of the handwaving.  Where is it costing the ISP
more when the user exceeds 12G/month?

Think very carefully about that before you answer.  If it was arranged
that every customer of the ISP in question were to go to 100% utilization
downloading 12G on the first of the month at 12:01AM, it seems clear to
me that you could really screw up 95th.

Note: I'm assuming the quota is monthly, as it seems to be for most
AU ISP's I've looked at, for example:

Yes most are monthly based on GB.

capacity is being stifled by ISP's that are stuck back
in speeds (and policies) appropriate for the year 2000.  

Imagine a case (even in the largest of ISP's), where there are no
quotas, and everyone has a 10Mbps connection.

I'm imagining it.  I've already stated that it's a problem.

I don't think there is an ISP in existence that has the infrastructure
capacity to carry all of their clients using all of the connections
simultaneously at full speed for long extended periods.

I'll go so far as to say that there's no real ISP in existence that
could support it for any period.

As bandwidth and throughput increases, so does the strain on the
networks that are upstream from the client.

Obviously.

Unless someone pays for the continuously growing data transfers, then
your 6Mbps ADSL connection is fantastic, until you transit across the
ISP's network who can't afford to upgrade the infrastructure because
clients think they are being ripped off for paying 'extra'.

Now, at your $34/month for your resi ADSL connection, the clients call
the ISP and complain about slow speeds, but when you advise that they
have downloaded 90GB of movies last month and they must pay for it, they
wont. Everyone wants it cheaper and cheaper, but yet expect things to
work 100% of the time, and at 100% at maximum advertised capacity. My
favorites are the clients who call the helpdesk and state "I'm trying to
run a business here" (on their residential ADSL connection).

90GB/mo is still a relatively small amount of bandwidth.  That works out 
to around a quarter of a megabit on average.  This is nowhere near the 
"100%" situation you're discussing.  And it's also a lot higher than the
12GB/mo quota under discussion.

What are we missing out on because ISP's are more interested in keeping
bandwidth use low?  

I don't think anyone wants to keep bandwidth use low, it's just in order
to continue to allow bandwidth consumption to grow, someone needs to pay
for it.

How about the ISP?  Surely their costs are going down.  Certainly I know
that our wholesale bandwidth costs have dropped orders of magnitude in 
the last ~decade or so.  Equipment does occasionally need to be replaced.
I've got a nice pair of Ascend GRF400's out in the garage that cost $65K-
$80K each when originally purchased.  They'd be lucky to pull any number
of dollars these days.  It's a planned expense.  As for physical plant,
I'd imagine that a large amount of that is also a planned expense, and is
being paid down (or already paid off), so arguing that this is somewhere
that a lot of extra expense will exist is probably silly too.

What fantastic new technologies haven't been developed
because they were deemed impractical given the state of the Internet?

Backbone connections worth $34/month, and infrastructure gear that
upgrades itself at no cost.

Hint: that money you're collecting from your customers isn't all profit.

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.


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