NTP includes error budget calculations at every level. You should be able to demonstrate the difference between directly using a stratum 1 appliance compared to using higher-strata intermediate NTP servers simply by observing the root dispersion on the client.
I suspect you are correct that the benefit is not worth the cost, but convince yourself with measurement. Using FreeBSD instead of Linux for the intermediate servers will probably give better results, if that is a possibility, give that a test as well. I would also encourage you to consider using NTPv4 in preference to NTPv3 where it is practical, but especially on the intermediate servers. A lot has improved in NTP since version 3. Finally, while it is true you can improve scalability using broadcast or multicast, it also requires extra configuration to provide matching keys on both sides, or using the "disable auth" option which is not recommended. NTP uses very few resources even with hundreds or thousands of unicast clients, as each client polls at most once per minute and typically, after stabilizing, once per 17 minutes (1024 seconds for default maxpoll 10). Processing each packet and replying is very fast, so even after a power outage when many clients are starting at once, I would expect even relatively decrepit hardware to have no problem keeping up with the traffic. With 10,000 clients polling a single server every 64 seconds, the average rate is 156 packets per second in and out each 48 bytes long. I bet your existing servers could handle that rate easily. Cheers, Dave Hart _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
