John Heidemann

Trinocular: Understanding Internet Reliability Through Adaptive Probing

TitleTrinocular: Understanding Internet Reliability Through Adaptive Probing
Publication TypeConference Paper
Year of Publication2013
AuthorsL. Quan, J. Heidemann, and Y. Pradkin
Conference LocationHong Kong, China

Natural and human factors cause Internet outages–-from big events like Hurricane Sandy in 2012 and the Egyptian Internet shutdown in Jan.%7e2011 to small outages every day that go unpublicized. We describe \emphTrinocular, an outage detection system that uses active probing to understand reliability of edge networks. Trinocular is \emphprincipled: deriving a simple model of the Internet that captures the information pertinent to outages, and populating that model through long-term data, and learning current network state through ICMP probes. It is \emphparsimonious, using Bayesian inference to determine how many probes are needed. On average, each Trinocular instance sends fewer than 20 probes per hour to each /24 network block under study, increasing Internet ``background radiation'' by less than 0.7%. Trinocular is also \emphpredictable and \emphprecise: we provide known precision in outage timing and duration. Probing in \emphrounds of 11 minutes, we detect 100% of outages one round or longer, and estimate outage duration within one-half round. Since we require little traffic, a single machine can track 3.4M /24 IPv4 blocks, all of the Internet currently suitable for analysis. We show that our approach is \emphsignificantly more accurate than the best current methods, with about one-third fewer false conclusions, and about 30% greater coverage at constant accuracy. We validate our approach using controlled experiments, use Trinocular to analyze two days of Internet outages observed from three sites, and re-analyze three years of existing data to develop trends for the Internet.