Network timekeeping a potentially dangerous obstacle to the Internet of Things, according to NIST
Fri 20 Mar 2015
According to the National Institute of Standards and Technology (NIST), the tolerant standards that existing networks maintain for accuracy of time are not likely to be adequate for the kind of critical decisions that will be required for a future dominated by the Internet of Things.
A recent report [PDF] by NIST entitled ‘Time-Aware Applications, Computers, and Communication Systems (TAACCS)’ concludes ‘A new economy built on the massive growth of endpoints on the internet will require precise and verifiable timing in ways that current systems do not support. Applications, computers, and communications systems have been developed with modules and layers that optimize data processing but degrade accurate timing,’
Discussing the report, which was written by NIST’s Marc Weiss and seven experts in the academic and industrial spheres, NIST PIO Chad Boutin comments that much-vaunted new technological developments such as self-driving cars and telemedical surgical suites will require a precision of timing far in excess of network standards. “For example,” he writes “for a driverless car to decide whether what it senses ahead is a plastic bag blowing in the wind or a child running, its decision-making program needs to execute within a tight deadline. Yet modern computer programs only have probabilities on execution times, rather than the strong certainties that safety-critical systems require,”
To illustrate the problem further, the report’s lead writer Weiss telescopes the issue to the possibility of synchronising your watch with that of a friend by means of snail mail. “That’s the equivalent of how accurate the timing of messages are in computers and systems right now,” he says. “The transfer delay must be accounted for to do the things that are expected of the IoT,”
The report recommends that IoT-enabled systems which have need of critically accurate time should use networked components built from scratch. The report cites the Google Spanner Project [PDF] as a possible model for the approach that will be necessary for the development of IoT-critical network timekeeping. Spanner is a global and scalable distributed database which uses an innovative world-time API, called TrueTime to expose clock uncertainty, but the program’s developers admit that in its current state the TrueTime API ‘may noticeably affect performance’.