Steven Keller wrote:
My question to the list is should I use pool.nts.org or is there some
other way to accomplish what I need? I don’t want to end up on some
black list somewhere because my devices are taxing the network.
A thousand clients that query time with a 6 hour interval will not be a
problem or even noticeable. Just make sure you don't hardcode any time
server IP addresses into your device. Maybe you could even use a domain
that you control to direct the clients to whatever service you would
like them to get time from. I.e. you could set up your devices to query
time from "mydevicetime.domain-i-control.com" and then by adjusting the
DNS at domain-i-control.com you could make
mydevicetime.domain-i-control.com to be a CNAME to pool.ntp.org, for
example. If in some point of time in the future you want to change away
from pool.ntp.org, you'd just change the DNS at domain-i-control.com.
For that small amount of clients you could easily run your own time
server if you wanted as well and that way by monitoring your time server
also make sure all your clients update their time regularly.
Some more general advice on the client that came to mind:
- don't hardcode any server IP addresses (yeah I'm repeating myself, but
this is important).
- don't do the time queries on some fixed time like 00:00:00, 06:00:00
etc, but count an interval from the start of the device or something
similar that causes the queries between clients to be at least
semirandomly distributed. The idea is to not have all your clients ask
for the time simultaneously, which would cause an unnecessary load spike.
- check the reply from the time server for validity and not just for the
time. If the NTP packet contains a KOD (leap bits set to unsynchronized
and stratum set to zero), pick another server to query time from.
Maybe it would be useful to have some kind of ground rules somewhere in
the web for developing (embedded) (S)NTP clients, from the point of the
time providers and preventing abuse. Maybe there are, I just haven't
looked.. Anyway the uwisc case
http://www.cs.wisc.edu/~plonka/netgear-sntp/ is a good read for anyone
developing time clients.
Tapio
_______________________________________________
timekeepers mailing list
[email protected]
https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
