[131985] in North American Network Operators' Group
RE: Current trends in capacity planning and oversubscription
daemon@ATHENA.MIT.EDU (Holmes,David A)
Wed Nov 10 14:15:04 2010
Date: Wed, 10 Nov 2010 11:14:46 -0800
In-Reply-To: <alpine.GSO.2.00.1011092327280.10788@clifden.donelan.com>
From: "Holmes,David A" <dholmes@mwdh2o.com>
To: "Sean Donelan" <sean@donelan.com>,
<nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Sometimes it is a hard sell, but the factor most overlooked when
designing high speed networks is that of designing for low latency.
Bandwidth and over/under subscription are only part of the network
design. Low latency networks (regional RTTs of 1-5 milliseconds; campus
RTTs in the sub millisecond range for GiGE, and microsecond range for 10
GiGE) by their nature solve a lot of QoS problems, often relegating QoS
as a method to be used in emergency cases only, such as DoS attacks.
Here is something I have been thinking is not too far over the horizon:
commodity 48 port x 10/100 GiGE switches; 10 GiG NICs on the desktop;
commodity-priced 10,40, or 100 GiGE WAN links; while user bandwidth
requirements rise at a much slower rate. Some switch vendors even today
have 48 port 10 GiGE switches in the $25K range.
My rule of thumb is that 1 GiGE link is an order of magnitude lower
latency than a 100 Mbps link, and a 10 GiGE link is an order of
magnitude lower latency than a GiGE link. =20
-----Original Message-----
From: Sean Donelan [mailto:sean@donelan.com]=20
Sent: Tuesday, November 09, 2010 9:26 PM
To: nanog@nanog.org
Subject: Current trends in capacity planning and oversubscription
While the answer is always it depends, I was wondering what the current=20
rules of thumb university network engineers are using for capacity=20
planning and oversubscription for resnets and admin networks?
For K-12, SETDA (http://www.setda.org/web/guest/2020/broadband) is=20
recommending:
- An external Internet connection to the Internet Service Provider of at
least 100 Mbps per 1,000 students/staff
- Internal wide area network connections from the district to each
school=20
and between schools of at least 1 Gbps per 1,000 students/staff
How does that compare with university and enterprise network rules of=20
thumb?
