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The dartmouth/campus dataset (v. 2009-09-09)  >  the snmp traceset

There are 3 traces in this traceset
last modified
2008-09-12
reason for most recent change
SNMP Traceset is resanitized.
short description

Records of SNMP polling at Dartmouth College.

description

The traceset of polling every AP every five minutes, during Fall term 2001, Spring term 2002, Fall term 2003 and Winter term 2004. The Fall 2001 data was used for [MobiCom 2002 paper]. The 2003/4 data was used for [MobiCom 2004 paper].

We recommend only using the 2003/4 data. See this important note about problems with the 2001/2002 SNMP dataset. Any questions about the 2001/2 data will go into our LBE (Less than Best Effort) queue, i.e., they may not be answered... please use the 2003/4 data instead.

release date
2004-11-09
date/time of measurement start
2001-09-14
date/time of measurement end
2004-02-28
methodology

We used the Simple Network Management Protocol (SNMP) to poll each AP every five minutes, querying AP and client-specific counters. AP-specific variables included inbound/outbound bytes, packets and errors, and the clients associated with a given AP. Client-specific variables included MAC and IP addresses, signal strength and quality.

sanitization

To sanitize the data, we randomly (but consistently) mapped the MAC address field into a randomly chosen MAC of the same vendor, and we mapped all IP addresses using a prefix-preserving sanitizer.

disruptions to data collection
There were unfortunate gaps in the data collection, generally caused by power failures.
limitation

We have no way to distinguish periods with no clients from periods when the AP was off or unreachable. We also have no way to detect an AP reboot or reset, which reset all of the per-client counters reported here. Thus it is critical to take care when interpreting the per-client byte counts... a counter can be reset or roll over between two polls, and the delta can thus appear to be negative (or, in unsigned math, a very large number).

error
In 2001/2 data, the perl scripts that performed the SNMP queries suffered from some problems, in that they queried inappropriate SNMP values, or misunderstood the meaning of other values. This data was also used in a subsequent analysis. The same scripts were used to collect data for a subsequent study of another wireless network. See http://www.cs.dartmouth.edu/reports/abstracts/TR2003-480/
 the dartmouth/campus/snmp/fall01 trace
 the dartmouth/campus/snmp/spring02 trace
 the dartmouth/campus/snmp/fall0304 trace
 how to cite this traceset