[99828] in North American Network Operators' Group
RE: Why do some ISP's have bandwidth quotas?
daemon@ATHENA.MIT.EDU (andrew2@one.net)
Fri Oct 5 13:12:35 2007
Reply-To: <andrew@profitability.net>
From: <andrew2@one.net>
To: "'Joe Greco'" <jgreco@ns.sol.net>
Cc: <nanog@merit.edu>
Date: Fri, 5 Oct 2007 13:12:35 -0400
In-Reply-To: <200710051558.l95FwDXC022755@aurora.sol.net>
Errors-To: owner-nanog@merit.edu
Joe Greco wrote:
>> 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.
First, the total transfer vs. 95%ile issue. I would imagine that's just a
matter of keeping it simple. John Q. Broadbanduser can understand the
concept of total transfer. But try explaining 95%ile to him. Or for that
matter, try explaining it to the average billing wonk at your average
residential ISP. As far as the 12GB cap goes, I guess it would depend on
the particular economics of the ISP in question. 12GB for a small ISP in a
bandwidth-starved country isn't as insignificant as you make it sound. But
lets look at your more realistic second whatif:
> 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.
As you say, 90GB is roughly .25Mbps on average. Of course, like you pointed
out, the users actual bandwidth patterns are most likely not a straight
line. 95%ile on that 90GB could be considerably higher. But let's take a
conservative estimate and say that user uses .5Mbps 95%ile. And lets say
this is a relatively large ISP paying $12/Mb. That user then costs that ISP
$6/month in bandwidth. (I know, that's somewhat faulty logic, but how else
is the ISP going to establish a cost basis?) If that user is only paying
say $19.99/month for their connection, that leaves only $13.99 a month to
pay for all the infrastructure to support that user, along with personnel,
etc all while still trying to turn a profit. In those terms, it seems like
a pretty reasonable level of service for the price. If that same user were
to go direct to a carrier, they couldn't get .5Mbps for anywhere near that
cost, even ignoring the cost of the last-mile local loop. And for that same
price they're also probably getting email services with spam and virus
filtering, 24-hr. phone support, probably a bit of web hosting space, and
possibly even a "backup" dial-up connection.
Andrew
