We discuss the collection, analysis and visualization of four forms of Internet traffic data: topology, workload, performance, and routing. Topology data can describe network link infrastructure at a variety of layers. Topology measurement and analysis can reveal macroscopic characteristics of the global Internet, e.g., `how big and what constitutes the Internet `core'?', as well as provide parameters to topology-generator models. Workload measurements involve the passive monitoring of traffic as it traverses a link or router, and allows analysis of distributions of traffic protocol, packet size, interarrival times, geographic flow, and per-user bandwidth consumption. Performance measurements typically involve active probing of traffic into the network to assess latency or throughput characteristics of paths. Broad scale latency measurements (i.e., to thousands of relevant hosts) at reasonable granularity can provide a database for isolating global problems within the infrastructure, as well as assessing service quality by country or other granularity of interest. Routing data includes analysis from Border Gateway Protocol (BGP) routing tables, which reflect relationships between individual Autonomous Systems (ASes) at a given point in time. For each area of measurement, we show state-of-the-art examples of visualization and analysis and highlight the research priorities. We also show instances of correlation among different measurement type, e.g., how actual (probed) topology differs from BGP-articulated topology (not to mention shortest path); how latency and throughput relate to other measures of path `length'; how workload and routing changes affect performance. Finally, we describe an infrastructural application of CAIDA's macroscopic topology mapping project (skitter), which focuses on assessing the optimality of root DNS server placement.

K.C. Claffy is founder and principal investigator of the Cooperative Assocication for Internet Data Analysis (CAIDA), based at the San Diego Supercomputer Center. Her research focuses on collection, analysis and visualization of wide-area Internet data on topology, workload, performance, and routing. CAIDA seeks, through the development of neutral, open tools and methodologies, to promote cooperation among Internet Service Providers (ISPs) in face of commercialization and competition, and to meet engineering and traffic analysis requirements of the commercial Internet community. dr. claffy recieved her M.S. and Ph.D. degrees in Computer Science from the University of California, San Diego. Evi Nemeth, a faculty member in computer science at the University of Colorado, has managed UNIX systems for the past 20 years, both from the front lines and from the ivory tower. She is co-author of the UNIX System Administration Handbook.