SDI Seminar

Speaker: Stefan Savage, University of Washington

Date: July 19, 1999
Time: Noon
Place: Wean Hall 8220

Sting: a TCP-based Network Measurement Tool


Understanding wide-area network characteristics is critical for evaluating the performance of Internet applications. Unfortunately, measuring the end-to-end network behavior between two hosts can be problematic. Traditional ICMP-based tools, such as ping, are easy to use and work universally, but produce results that are limited and inaccurate. Measurement infrastructures, such as NIMI, can produce highly detailed and accurate results, but require specialized software to be deployed at both the sender and the receiver. In this paper we explore using the TCP protocol to provide more accurate network measurements than traditional tools, while still preserving their near-universal applicability. Our first prototype, a tool called "sting", is able to accurately measure the packet loss rate on both the forward and reverse paths between a pair of hosts. We describe the techniques used to accomplish this, how they were validated, and present our preliminary experience measuring the packet loss rates to and various Internet web servers.


Stefan Savage is a computer science Ph.D. candidate at the University of Washington, where he's currently exploring resource management issues for wide-area networks. Stefan's interests broadly encompass "experimental systems" and his previous projects have included automated software testing, extensible operating system design, weak-redundancy disk arrays and real-time scheduling policies. Before enrolling at UW, he received a B.S. in Applied History from Carnegie Mellon University and spent several years as a staff member with the real-time systems group in CMU's School of Computer Science. Stefan is generally a good guy and only writes about himself in the third person when specifically requested.