Limit monitors per server

[abh]

https://community.ntppool.org/t/exclude-local-monitors-from-selection/3595 (thanks to @hart-NTP)

• Exclude monitors in the same /24 (or ::/48) from monitoring a server (even testing)

For active monitors:

• Limit monitors in the same ASN as the server to 1 active monitor.
• Limit monitors sharing an ASN to 2 to server.
• Limit monitors per account to 2 per server (or 1, with exceptions for some NTP Pool accounts?).

Maybe have similar limits for testing monitors (though higher numbers)?

Limit the total number of testing monitors to X per server with some logic for replacing the poorest performing monitor with a "standby" monitor every X hours / days?

[hart-NTP]

The ASN limiting is along the same lines and makes sense to me. I hope and suspect it won't cause any paucity of monitors for individual servers.

I also like the idea of limiting the monitors per account assigned to a server, with exceptions for monitors run by pool staff as needed.

[ON5HB]

I agree with https://community.ntppool.org/t/exclude-local-monitors-from-selection/3595/6 Csweeney, there isn't a problem.

I fail to see the problem, as there isn't one.

[avijc]

Five of my beta monitors are in the same AS, but in four countries: Poland, Singapore (x2), Netherlands, Australia. I would say that the monitoring performance of, say, Dutch and Australian monitors are probably sufficiently different to allow them both, even if they're in the same AS. On the other hand, the two monitor servers in Singapore are probably fairly equivalent and there's no need to use both of them to monitor some specific server.

Generally, I would favour AS-based classification as proposed, but replacing AS with an AS+country tuple as the network identifier. Anything based on a specific netmask like /16 or /24 or /48 would end up being a bad choice for some people, ie. there is no netmask size that would be suitable for everyone.