chetal@pyrps5.pyramid.com (Pradeep Chetal) (06/20/91)
I just picked up the NTP version 3 distribution from udel.edu and
compiled the system w/o any problems. However, while testing it out I
have a /etc/ntp.conf with just one peer.The peer has been up all the
time and if I change the time on my system it is updated from the peer
properly. However every now and then I see the following message:
Jun 19 20:35:15 mrfreeze unix: ntpd[7110]: Lost NTP peer 129.214.10.151
at various intervals ranging from 4 minutes to 20 minutes. Has anyone
else seen this behaviour?
Thanks,
/Pradeep
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Pradeep Chetal UUCP: ...!{decwrl,sun,uunet}!pyramid!chetal
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Pyramid Technology Phone: (415) 335-8227 (O)
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Mountain View, CA 94043 (415) 335-8845 (FAX)Craig_Everhart@TRANSARC.COM (06/20/91)
I'm sure I'll get corrections on this if I falter, but I'll answer anyway. The message just means that the skew between the clocks (the local clock and the remote one that it's trying to synch with) is larger than some threshhold, about 128 milliseconds. When ntpd synchs with a peer that's more than the threshhold off from the local clock, it does it by setting the time rather than calling adjtime(), and it clears the peer-synchronization filter (array of saved time offsets from the remote peer) in the process. This prints the ``Lost NTP peer...'' message. What it really means is ``Cleared samples from NTP peer...''. In short, it's not a problem with the remote peer, but it may be a subtle indication that your local clock (or the peer's clock) doesn't keep very consistent time--that one system or the other locks out clock updates for a while, e.g. over long interrupt-service times. Or that some process besides ntpd is using adjtime() to dink with the local clock. Craig
chetal@pyrps5.pyramid.com (Pradeep Chetal) (06/22/91)
>I'm sure I'll get corrections on this if I falter, but I'll answer anyway. > >The message just means that the skew between the clocks (the local clock >and the remote one that it's trying to synch with) is larger than some >threshhold, about 128 milliseconds. When ntpd synchs with a peer that's >more than the threshhold off from the local clock, it does it by setting >the time rather than calling adjtime(), and it clears the >peer-synchronization filter (array of saved time offsets from the remote >peer) in the process. This prints the ``Lost NTP peer...'' message. >What it really means is ``Cleared samples from NTP peer...''. > >In short, it's not a problem with the remote peer, but it may be a >subtle indication that your local clock (or the peer's clock) doesn't >keep very consistent time--that one system or the other locks out clock >updates for a while, e.g. over long interrupt-service times. Or that >some process besides ntpd is using adjtime() to dink with the local >clock. > > Craig I followed a little more on the "Lost NTP peer" problem and found that whenever it happens the "peer->estdisp" is greater than NTP_MAXWGT which is the maximum allowable dispersion and therefore it fails in the sanity_checking() procedure. This apparently has nothing to do with the 128 ms (I guess you are referring to #define CLOCK_MAX 0.128 /* maximum aperture (milliseconds) */) which anyways is .512 for me as I don't have XTAL defined. BUT then I just started playing with NTP and haven't looked at complete source. Actually the "peer->estdisp" is greater than NTP_MAXWGT alot of times BUT then sys.peer (in select_clock routine) is NULL most of the time and we don't see the message. Only sometimes is sys.peer non-null and I see this message. So I am NOT sure if the skew clock problem between local & remote peer is the reason. Meanwhile I am also trying to get xntp to work on our systems. Rest everything out here is NTP. I thought I will be able to use "xntp" with peer's & server's defined as "version 1" in the /etc/ntp.conf file w/o any other changes. "xntpd" starts up fine BUT I don't think it is talking to other "ntpd" peers & servers. Do I have to do anything other than this (version) so that xntpd can talk to other peer & server "ntpd" daemons. Thanks, /Pradeep