Rich wrote: [] > Recently, in order to spread out my time base somewhat, I tried adding > some outside servers (using the *.pool.ntp.org DNS names) to my NTP > configurations. Since doing this, I've noticed that the nearby > (Stanford) servers are uniformly "off" by several milliseconds, in > comparison to more distant servers. Here, for example, is some output > from the ntpq "peers" command (with host names turned off) on one of > my servers: [] > I also see that the above machine is currently syncing to a server in > Germany (delay = 171 msec) -- possibly because it's on stratum 1. (I > submitted a separate posting questioning whether stratum-1 servers > should really be in the pools, but that's a separate issue.) > > Is this sort of behaviour to be expected? Does this mean that the NTP > algorithm ought to be giving more weight to servers with shorter > delays? Or, perhaps, does it suggest that there might be something > wrong with the Stanford servers that is making them all cluster around > a time that is several milliseconds different from the rest of the > world? > > Rich Wales
Rich, Is it possible that your connection to one lot of servers is asymmetrical - in the sense of having more delay outbound than inbound or vice-versa? NTP cannot compensate for such asymmetry, and could cause the apparent offsets you have seen. You could also issue NTPQ commands against these remote servers. I have also seen NTP make what appear to be unusual choices for sync servers, and reported it here. As I now use my own stratum-1 servers and the "prefer" option, the problem has gone away. I was never completely convinced about such behaviour. Cheers, David _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
