A quick survey of the 600 clients that show up in the output of 'ntpdc -c monlist' and histogramming based on the 'avgint' column (average poll interval, due to integer math very often it gets rounded down to the next lowest integer) shows that:
There's a wide spread of poll intervals, most of them not falling into any obvious peak but spread vaguely like 1/log(n) from a few seconds up to 1200 seconds (where the rollover buffer cuts off). There are some discernable peaks: Twelve have an average poll interval of 4 seconds or less, some have racked up well over 100000 to 200000 polls in the past few days since I reset the statistics. There's a small spike of 4 clients at 29/30 seconds, most of them poll exactly at :00 and :30 seconds after each minute. There's a small spike of 7 clients at 31 or 32 seconds, presumably from clients polling every 32 seconds, this is more aggressive than ntpd would normally be set I guess. There's a spike of 5 clients at 59/60 seconds, presumably from clients polling once a minute. There's a spike of 25 clients at 63 or 64 seconds, presumably from clients polling once every 64 seconds. This would be an interval common to ntpd, but one would expect it to back off and poll less frequently after a while, but that's not what I see. There's a very tiny spike of 3 clients at 255 seconds, presumably from clients polling once every 256 seconds (again a possible ntp polling interval). There's a surprising spike of 11 clients at 624 or 625 seconds. I'm not sure what kind of client this is, I don't see much numerology in a poll period of 625 seconds. (Well, there's 625 lines in some TV format, but that can't be related, can it?) All identify their NTP version as "3". And there's a known clump of clients polling once every 1023 or 1024 seconds, probably nominally-configured ntpd's that have backed off their poll interval. At the very top of each hour, there are several hundred requests from clients that do not reappear for another hour. Complete bozos as far as I can determine, but their network load doesn't really disrupt life for the clients that actually know better than to launch all their queries at the top of the hour. The above statistics were generated while I was very nicely locked as a stratum 1 to a radio refclock. If I go unlocked, the characteristic of polling clients tends to pick up a lot of bozos that poll me much more often. Tim. _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
