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GEMINI : Active Network Measurements. Martin Swany, Indiana University. Overview. GEMINI is an I&M system based on perfSONAR /LAMP, INSTOOLS and Periscope (updated perfSONAR protocols) Measurement i nfrastructure , support services , schemas/metadata
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GEMINI:Active Network Measurements Martin Swany, Indiana University
Overview • GEMINI is an I&M system based on perfSONAR/LAMP, INSTOOLS and Periscope (updated perfSONAR protocols) • Measurement infrastructure, support services, schemas/metadata • Active measurements aren't that special • all measurements should have accurate timestamps • all measurements may perturb a user's experiment • all measurements may perturb other measurements • Active measurements do affect multiple hops
Active Measurement Tools • OWAMP – One Way Active Measurement Protocol • Can separate forward and reverse path characteristics • Delay measurements – depends on clock synchronization • BWCTL – “Bandwidth controller” • Wraps bulk transfer test tools like Iperf • Can provide mutual exclusion for ongoing tests • Ping – simple but ubiquitous • 802.1ag defines L2 ping (to be included soon)
GEMINI at GEC 14 • User marks which nodes are 'active MPs’ in request RSpec • Active measurement software infrastructure currently runs on user nodes • Instrumentize process installs all the software: • iperf, bwctl, owamp tools • perfSONAR services (pSBUOY, PingER) • Web UI provides centralized configuration administration for active measurements • Enable services and tools (bwctl, owamp daemons) • Configure regular testing • Nodes run a local service that updates configuration, starts/stops daemons and performs maintenance
Performing Active Measurements On-Demand • OWAMP and BWCTL permit third-party on-demand measurements • one-way latency, jitter, loss and throughput metrics • must have daemons enabled and running on endpointsand OWAMP requires coordinated clocks • These tools also provide rudimentary coordination • e.g. BWCTL will serialize throughput measurements on same node Regular Testing • Users can configure regular OWAMP, BWCTL and Ping testing • Data is stored on nodes that perform the measurements (MySQL) • perfSONAR services store metadata about measurements and make the data available for querying • metadata includes: endpoints, tool and parameters used • data always includes a timestamp • Data from regular testing can be visualized in browser or queried (for raw data)
Future Issues • Single framework for measurements • make it easy to extend, add new tools and metrics • reuse scheduling, authentication, coordination, naming, metadata • provide APIs and schemas for the data/metadata • on-demand testing still depends on tools • Infrastructure • Potentially dedicated measurement nodes with user-accessible data – depends on AA • Coordination, sharing of active measurements • Selective/on-demand installation of software • Proper quantification of measurement errors and experiment perturbation • Instrumentation of the measurement software.