[140992] in North American Network Operators' Group
Re: Contention/Oversubscription maths
daemon@ATHENA.MIT.EDU (Jared Mauch)
Fri May 27 08:45:46 2011
From: Jared Mauch <jared@puck.nether.net>
In-Reply-To: <4DDF959B.2050601@memetic.org>
Date: Fri, 27 May 2011 08:45:36 -0400
To: Adam Armstrong <lists@memetic.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On May 27, 2011, at 8:14 AM, Adam Armstrong wrote:
> No SLA, residential customers.
I would watch out for the 'abusers' in this case, and have the =
capability to rate-limit the ports if necessary. Some hardware doesn't =
deal well with 'small' buckets of rate-limiting, eg: taking a 1G port to =
1M.
I'm interested in your operational results, as i've had a few general =
ASSumptions i've offered in this space:
- Most people are going to be limited by their wireless gear (few people =
care to run wired very far)
- Most servers on the far-end aren't going to be fast enough to cope
- Most people aren't going to spend time debugging network problems
- Some percentage of users are going to run a torrent or something else =
and flatline their port. You need to be able to police them at a =
reasonable bandwidth cap, eg: 10M if they have 1G, but that's 1% and =
many dumber switches won't go under 10%.
The other solution is to just throw more bandwidth at the problem. Make =
sure your switches can easily take a 10G or n*10G uplink.
I'd expect that the single bursty user is going to drown out the rest of =
them into the noise, as they will likely plug in directly and have no =
wireless hops that limit their speeds.
One of my friends operates a WISP in this area and has periodic issues =
with the heavy usage users and wonders what they're doing with that =
150GB of data they "download" in a month.
- Jared=
