Dartmouth College campus-wide wireless network: research
Dartmouth really has wireless everywhere, including the
Dartmouth Skiway (left).
Facts about Dartmouth's wireless network.
Dartmouth gives free VoIP software to all students,
free local and domestic long-distance calling,
and they all use the campus WiFi network.
Wired magazine ran a
on wireless at Dartmouth, which mentions the results of our 2001 study.
Discovery Channel Canada also ran a three-part television
story in 2002:
More info, more press coverage
David Kotz, Tristan Henderson, Ilya Abyzov, Brad Noblet
As of Fall 2003, Dartmouth College's campus-wide WiFi network has over
550 Cisco access points. In our previous work (below) we extensively
characterized the nature of Wi-Fi usage by over 3000 campus WiFi
users, data that has been significantly useful to network planners,
network designers, and application developers. Today, we are poised
to replace our campus telephone system with a complete Cisco VoIP
solution, installing over 6000 Cisco VoIP phones and SoftPhones in the
next two years. We expect many SoftPhones and Wi-Fi handsets to be in
use, so VoIP should have a significant impact on our wireless network.
We will take advantage of this incredible opportunity to monitor our
wireless network before and after the introduction of wireless VoIP
clients, to measure the characteristics of voice users and their
traffic, to measure the load on the wireless network, and to evaluate
the impact of voice on the Cisco access points and on the network.
Data collection began in November 2003.
Research supported by the Cisco Systems
University Research Program
Understanding usage patterns in wireless local-area networks (WLANs)
is critical for those who develop, deploy, and manage WLAN technology,
as well as those who develop systems and application software for
wireless networks. This paper presents results from the largest and
most comprehensive trace of network activity in a large, production
wireless LAN. For eleven weeks we traced the activity of nearly two
thousand users drawn from a general campus population, using a
campus-wide network of 476 access points spread over 161
buildings. Our study expands on those done by Tang and Baker, with a
significantly larger and broader population.
We found that residential traffic dominated all other traffic,
particularly in residences populated by newer students; students are
increasingly choosing a wireless laptop as their primary
computer. Although web protocols were the single largest component of
traffic volume, network backup and file sharing contributed an
unexpectedly large amount to the traffic. Although there was some
roaming within a network session, we were surprised by the number of
situations in which cards roamed excessively, unable to settle on one
access point. Cross-subnet roams were an especial problem, because
they broke IP connections, indicating the need for solutions that
avoid or accommodate such roams.
David Kotz <firstname.lastname@example.org>
Last modified: Wed Jan 12 14:50:26 2005