Spoon wrote: > Richard B. gilbert wrote: > >> Spoon wrote: >> >>> Richard B. gilbert wrote: >>> >>>> Spoon wrote: >>>> >>>>> I've read this page: >>>>> http://ntp.isc.org/bin/view/Support/HowToCalibrateSystemClockUsingNTP >>>>> which explains how to let NTP determine the frequency offset (skew). >>>>> >>>>> I have a strange request: >>>>> >>>>> Is it possible to run NTP in a mode where it does not try to correct >>>>> the time offset, but only correct the frequency offset (skew)? >>>>> >>>>> In other words, assume my clock says it is some time last year, and >>>>> gains 1 second every day (11.6 ppm). I don't want NTP to either slew >>>>> or step my clock to the correct time, but I still would want it to fix >>>>> this 1 s per day (11.6 ppm) frequency offset. >>>>> >>>>> Has this ever been considered? >>>> >>>> >>>> What problem are you trying to solve? >>>> >>>> Most people want the correct time rather than simply a clock keeping >>>> the >>>> wrong time but one that ticks at one second per second. >>> >>> >>> I'll try to explain my situation in detail. >>> >>> Consider two systems, A and B. >>> >>> A sends ~1000 UDP packets per second to B. >>> >>> A timestamps each packet. >>> >>> These packets travel over an IP network, and suffer delay and jitter. >>> >>> B is supposed to re-send the packets it receives at the rate they >>> were originally sent by A. >>> >>> B buffers N packets. Then it sends the first packet in the queue, >>> computes the departure time of the next packet using the timestamps >>> provided by A, and sleeps until that departure time. >>> >>> If the clocks on A and B do not tick at the same rate, the buffer >>> used by B will either overflow or underflow. >>> >>> This is why I need A's clock and B's clock to tick at the same rate. >>> >>> But it is not important to me that A and B's clock give the same >>> absolute time. Was that clear or did I forget something important? >> >> >> ntpd should be able to both keep your clocks synchronized to the same >> time but also to the same rate. There WILL be startup transients but >> once the two machines are synchronized they should both have the same >> time, within a millisecond or two and be ticking at 1.000000 seconds >> per second. > > > If I start ntpd when the system boots, and let it run 60-90 minutes > before I start my application, then this solution works very well! > > However, my boss thinks it is unacceptable to have to wait so long to > start the application :-( > >> Is there some good reason why A's packets must be relayed through B? >> Does B do any processing of the packets or does it simply forward them? > > > B sends the packets it receives to a local device. Why do you ask? > > Regards.
I asked because I didn't understand why you were using server B to relay messages that it seemed that server A could send directly. _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
