Dartmouth College campus-wide wireless network: research

A project of the Center for Mobile Computing

Dartmouth really has wireless everywhere, including the Dartmouth Skiway (left).

We have been monitoring our network since 2001 for research purposes. Here is our PRIVACY POLICY. If you would like to use our collected data, please check out the CRAWDAD data archive.

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 story on wireless at Dartmouth, which mentions the results of our 2001 study.

Discovery Channel Canada also ran a three-part television story in 2002: Part 1, Part 2, Part 3.

More info, more press coverage

2003-04 study: Voice over IP

David Kotz, Tristan Henderson, Ilya Abyzov, Brad Noblet
Research supported by the Cisco Systems University Research Program

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.

2001-03 study: Network usage pattern

David Kotz, Kobby Essien, Pablo Stern
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 <dfk@cs.dartmouth.edu>
Last modified: Wed Jan 12 14:50:26 2005