> > I've heard that NTP acts funny when it tries to sync over an ADSL line. > > That seems to be the case indeed: > > 0 [EMAIL PROTECTED]:/home/folkert/www$ ntpq -c pe > > remote refid st t when poll reach delay offset > > jitter > > ============================================================================== > > GENERIC(0) .DCFa. 0 l 23 64 3 0.000 -17.386 > > 26.356 <- dcf77 receiver > > -keetweej.intran 130.149.17.8 2 u 810 1024 376 0.735 2.724 > > 0.084 <- other server on my lan
on the lan but it also syncs against an internet-host, that explains the offset being different from my the first entry in this list > > thegateap.intra .STEP. 16 u - 1024 0 0.000 0.000 > > 4000.00 <- other server on my lan this one also syncs against the internet when it is (it died for some unknown reason): thegateap.intra 130.149.17.8 2 u 22 64 2 5.008 18.163 0.001 > > And there it is: 20ms offset. From what I've heard this is caused by > > ADSL being asymetric. > > Now I was wondering, can't this be fixed by telling the NTP daemon how > > much asynchronous the line is? I mean: it can be easily measured what > > the down- and upload bandwidth is. > > My experience is that ADSL causes much smaller than 20ms delays. If you do > the math for NTP > packets which take two ATM frames you'll find it comes out to between 1 and 2 > ms depending on how > fast and how asymmetrical your line is (mine is 6000/608 yielding 1.281 ms > offset). Unless your > line is very odd the 20ms your are seeing is far more likely to be from > having the wrong propagation > delay in the DFC77 driver. Is there any way you know how I can fix this? This clock is configured this way: # mode 14, RAW DCF at 50baud server 127.127.8.0 mode 14 > After a lot of experimenting on my part I decided to give up on factoring out > the DSL offset and > live with the slight perceived error. Hmmm ok. So far it doesn't give any problems as things will sync always against internet NTP-servers, making the local DCF77 receiver rather useless. I'm a little afraid, though, that when all systems in my lan have a DCF77-ish (well, an MFS and HFS receiver) receiver, things will become very jumpy by switching back and forth between internet and local clock(s). Folkert van Heusden -- iPod winnen? --> http://keetweej.vanheusden.com/redir.php?id=62 -------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
