Abstract
Service Level Agreements (SLAs) define the performance guarantees made by Internet Service Providers (ISPs) in terms of packet delay, loss, variation and network availability. Violations of SLAs can have serious consequences in terms of lost revenues for customers and penalties for the ISP. In this talk, I will describe our recent work on SLA compliance monitoring, which focuses on assessing whether the performance characteristics in a service provider network are within specified bounds. To address this problem we have developed a comprehensive set of active probe-base measurement methodologies that enables accurate and efficient assessment of 1) packet loss rate, 2) mean delay and confidence intervals for delay quantile estimation, 3) delay variation (ie. jitter), and 4) delay quantiles for unmeasured paths. We implement these methods in a tool called SLAm, which we use to demonstrate the capabilities of our methods in a set of controlled laboratory experiments using different topologies and background traffic scenarios. We also extend the use of SLAm to the practical problems of detecting and localizing the occurrences of SLA violations in provider networks. This requires additional methods for selecting which paths to probe at a given point in time and then identifying the links on a path that are contributing to a violation event. We use a set of simulation-based experiments to show that these methods are able to accurately detect and localize performance violation events in a timely fashion and with lower probe overhead than prior methods.

BIO
Paul Barford is an associate professor in the computer science department at the University of Wisconsin-Madison where he has been since 2001. He received a BS in electrical engineering from the University of Illinois and a PhD in computer science from Boston University. He is the founder and director of the Wisconsin Advanced Internet Laboratory - a widely used network testbed sponsored by Cisco Systems and the NSF. His research is focused on developing new techniques for gathering information on the structure and dynamic behavior of the Internet. He is also focused on developing new methods for protecting networks and systems from malicious attacks, and is the founder of Nemean Networks, a network security start-up company. Prof. Barford has authored numerous publications in highly competitive journals and conferences. He has served on committees of many conferences including ACM SIGCOMM, SIGMETRICS ('10 TPC chair), IMC ('06 TPC chair), CCS and USENIX Security. He is a member of the ACM Internet Measurement Conference steering committee, an associate editor of IEEE/ ACM Transactions on Networking, and a voting member of the Board of Directors of the National LambdaRail.