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Internet of Things Endangered By Inaccurate Network Time, Says NIST
An anonymous reader writes: Current standards of network timekeeping are inadequate to some of the critical systems that are being envisaged for the Internet of Things, according to a report (PDF) by the National Institute of Standards and Technology (NIST). The report says, "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." NIST's Chad Boutin likens current network accuracy to an attempt to synchronize watches via the postal system, and suggests that remote medicine and self-driving cars will need far higher standards in order not to put lives at risk. He says, "modern computer programs only have probabilities on execution times, rather than the strong certainties that safety-critical systems require."
The network is not necessarily involved. The example given of a self-driving car talks about the amount of time taken to distinguish between a plastic bag blowing in the wind and a child running in front of the car. This is not "network" timekeeping, just regular real-time processing.
Nobody has ever depended on accurate time synch delivered over a network system with zero guarantee of packet delivery, let alone guarantee of delivery time. NTP has always just been "Good enough" to make sure your systems to be on the same date/time so things can synchronize in a somewhat organized fashion.
Anything requiring honestly accurate time synch has always relied on external synchronization schemes. Ultra-accurate clocks, sometimes synched with outside networks that /do/ have guarantee mechanisms.
But that was in the past. Long gone are the days of special 1000 dollar add on-cards for scientific and specialized computing applications.
Now you can get a GPS chip for 25 cents and draw a half-inch antenna on the outer edge of your PCB.. And guess what? High quality, accurate time sync that rivals the most expensive solutions from yesteryear. Fuck. The SoC that your IoT device is running on probably has half of that circuitry already built in (Along with Wifi, bluetooth, etc) so your GPS transceiver chip probably only costs half that.
Exactly. The vast majority of Internet-of-Things devices can solve the problem by just installing ntpd and being done with it. My refrigerator or coffee maker or dehumidifier don't need hyper-accurate timing, and in the past year my devices running ntpd have never been more than around a tenth of a second off, which is still more accurate than anything that I actually need.
I get that you may need hyper-accurate timing for some things, but if something is so critical that a few milliseconds of clock skew can kill people, it shouldn't be connected to the Internet anyhow!
It covers a wide berth of timing related topics and is information dense. I found no marketing BS in this paper at all.