Instrumentation for exact packet timings in networks

We design and implement a novel class of highly precise network instrumentation, capable of the first-ever capture of exact packet timings of network traffic. Our instrumentation — combining real-time physics test equipment with off-line postprocessing software — prevents interference with the system under test, provides reproducible measurements by eliminating non-deterministic error, and uses transparent and ubiquitous lab equipment and open-source software for ease of replication. We use our technique to perform in-situ observations of 10 Gigabit Ethernet packets in flight on optical fiber, showing improvements in timing precision of two to six orders of magnitude over existing methods of measurement, which generally employ software on commodity computer endpoints of network paths.