[ntp:questions] reachability register
Dear all, Thanks for your detailed reply. @Charles, if I unplug my 1-Gbit internet line then about 250 user are not happy. An my supervisor too. But I know how to simulate this. It happened on an internal ntp server with version 4.2.8p1 with a peer connection to another internal and 2 configured upstream server to the DMZ ( also internal ) But I have seen this behavior on this 2 ntp server at the DMZ too. Of course I didn't look at the source code. And obviously I will not understand it. @Brian, I read 3 times your information and tried to follow. Definitely I looked not only once after the change. So it was not only between request and reply. What I take with me: yes it can happen, it's a normal behavior. Thanks for your advice. Kind regards Hans ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] reachability register
Hello:
All I can say is, it does that sometimes. I think what might be
happening is that ntpq caught ntpd before the reachability register was
updated, although it updates that fairly early in the game. You can see the
code in proto.c in a recent source distribution, like here:
Tarball:
http://archive.ntp.org/ntp4/ntp-dev/ntp-dev-4.3.14.tar.gz
MD5 sum:
http://archive.ntp.org/ntp4/ntp-dev/ntp-dev-4.3.14.tar.gz.md5
If you want to see it work correctly and you are using Windows,
start the Meinberg NTP Monitor and set it to monitor your Internet-facing
NTP client. On a non-Windows O/S, just use the host command to set ntpq to
the Internet-facing NTP client and repeatedly send it the peers command.
In any case, then unplug your Internet modem and your router. Wait
a few seconds (~60), plug the modem back in, then after a few seconds (~30)
plug in your router. Then watch the Meinberg NTP Monitor or the ntpq peers
output of the reachability register. You should see something like the
following:
BinaryOctal
100 100
1001 201
11 3
111 7
17
137
1177
111 177
377
Charles Elliott
-Original Message-
From: questions [mailto:questions-
bounces+elliott.ch=comcast@lists.ntp.org] On Behalf Of MAYER Hans
Sent: Wednesday, April 8, 2015 9:23 AM
To: questions@lists.ntp.org
Subject: [ntp:questions] reachability register
Dear all,
I have a question about the reachability register. For my opinion this
is a left shift 8-bit register.
I looked in one of our internal ntp-server with ntpq and found a
value of 376 to a peer configured internal server. After waiting the
time difference between poll and when I can find the value of 377.
How is it possible ? For my understanding this could only happen after
8 times the poll interval. The next value should be 375 and after that
373. And so on shifting the 0-bit to the left.
Kind regards
Hans
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[ntp:questions] reachability register
Dear all, Thanks for your detailed reply. @Charles, if I unplug my 1-Gbit internet line then about 250 user are not happy. An my supervisor too. But I know how to simulate this. It happened on an internal ntp server with version 4.2.8p1 with a peer connection to another internal and 2 configured upstream server to the DMZ ( also internal ) But I have seen this behavior on this 2 ntp server at the DMZ too. Of course I didn't look at the source code. And obviously I will not understand it. @Brian, I read 3 times your information and tried to follow. Definitely I looked not only once after the change. SO it was not only between request and reply. What I take with me: yes it can happen, it's a normal behavior. Thanks for your advice. Kind regards Hans ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] reachability register
Dear all, Thanks for your detailed reply. @Charles, if I unplug my 1-Gbit internet line then about 250 user are not happy. An my supervisor too. But I know how to simulate this. It happened on an internal ntp server with version 4.2.8p1 with a peer connection to another internal and 2 configured upstream server to the DMZ ( also internal ) But I have seen this behavior on this 2 ntp server at the DMZ too. Of course I didn't look at the source code. And obviously I will not understand it. @Brian, I read 3 times your information and tried to follow. Definitely I looked not only once after the change. SO it was not only between request and reply. What I take with me: yes it can happen, it's a normal behavior. Thanks for your advice. Kind regards Hans ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] reachability register
On 4/8/2015 9:23 AM, MAYER Hans wrote: Dear all, I have a question about the reachability register. For my opinion this is a left shift 8-bit register. I looked in one of our internal ntp-server with ntpq and found a value of 376 to a peer configured internal server. After waiting the time difference between poll and when I can find the value of 377. How is it possible ? For my understanding this could only happen after 8 times the poll interval. The next value should be 375 and after that 373. And so on shifting the 0-bit to the left. You are mostly correct. You are missing only one small detail. The register gets shifted when NTP sends a packet and ORs in a one when it receives a packet. Thus, if the low order bit were zero because a packet got dropped, then your reasoning would be correct. However, if the low order bit were zero because you happened to look between the time a request was sent and a reply was received then what you observed is correct. -- Oracle http://www.oracle.com Brian Utterback | Principal Software Engineer Phone: +1 6038973049 tel:+1%206038973049 Oracle Systems/RPE Solaris Network 1 Oracle Dr. | Nashua, NH 03062 This space for sale or rent Green Oracle http://www.oracle.com/commitment Oracle is committed to developing practices and products that help protect the environment ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] reachability register
Dear all, I have a question about the reachability register. For my opinion this is a left shift 8-bit register. I looked in one of our internal ntp-server with ntpq and found a value of 376 to a peer configured internal server. After waiting the time difference between poll and when I can find the value of 377. How is it possible ? For my understanding this could only happen after 8 times the poll interval. The next value should be 375 and after that 373. And so on shifting the 0-bit to the left. Kind regards Hans ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
