Dear list readers -
Sorry to cause some additional noise on the list, but I am looking for help in building a strat1 or 2 time server. I have a Fedora Core 6 server running with the latest NTP server installed. What I am trying to do actually is build an authoritative or reference time server that we can use here for testing daylight saving time adjustments in our environment. After thinking about it, I have come to the sane conclusion that this wont work with a normal ntp server as it will constantly want to FIX the time back and my ntpclients wont pull time if the server is out of whack. So I need to build an ntp server that doesn't go out and sync with an outside source, that my clients can use in this test environment. So, my question is, just how do you build one?
Any insights and additional information would be greatly appreciated.
Michael Weiner
===================================
Cleveland Clinic is ranked one of the top 3 hospitals in America by U.S.News & World Report. Visit us online at http://www.clevelandclinic.org for a complete listing of our services, staff and locations.
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Weiner, Michael wrote:
Dear list readers -
Sorry to cause some additional noise on the list, but I am looking for help in building a strat1 or 2 time server. I have a Fedora Core 6 server running with the latest NTP server installed. What I am trying to do actually is build an authoritative or reference time server that we can use here for testing daylight saving time adjustments in our environment. After thinking about it, I have come to the sane conclusion that this wont work with a normal ntp server as it will constantly want to FIX the time back and my ntpclients wont pull time if the server is out of whack. So I need to build an ntp server that doesn't go out and sync with an outside source, that my clients can use in this test environment. So, my question is, just how do you build one?
Any insights and additional information would be greatly appreciated.
Michael Weiner
===================================
The only way that I know of to get this kind of a time source, is to actually have a strat1 or 2 time source in your location. We had this discussion here at the office a while back, since we ahve a strat2 cesium clock to sync all our SONET rings. Even then, if you don't have people actually syncing from the strat2 directly, and only have the ntp server syncing it, it will still technically be only a strat3 time source.
HTH.
-----Original Message----- From: fedora-list-bounces@redhat.com [mailto:fedora-list-bounces@redhat.com] On Behalf Of Mark Haney Sent: Tuesday, February 27, 2007 12:22 PM To: For users of Fedora Subject: Re: Building a strat1/2 time server
Weiner, Michael wrote:
Dear list readers -
Sorry to cause some additional noise on the list, but I am looking for help in building a strat1 or 2 time server. I have a Fedora Core 6 server running with the latest NTP server installed. What I am trying
to
do actually is build an authoritative or reference time server that we can use here for testing daylight saving time adjustments in our environment. After thinking about it, I have come to the sane
conclusion
that this wont work with a normal ntp server as it will constantly
want
to FIX the time back and my ntpclients wont pull time if the server is out of whack. So I need to build an ntp server that doesn't go out and sync with an outside source, that my clients can use in this test environment. So, my question is, just how do you build one?
The only way that I know of to get this kind of a time source, is to actually have a strat1 or 2 time source in your location. We had this discussion here at the office a while back, since we ahve a strat2 cesium clock to sync all our SONET rings. Even then, if you don't have people actually syncing from the strat2 directly, and only have the ntp server syncing it, it will still technically be only a strat3 time source.
HTH.
Mark -
Yes that's helpful. So is there no way I can say have a windows box connect to this server and pull its time successfully even though the ntp server is an hour behind, or say we roll the date forward to March 11, 2007? You can see where we are going with this as far as testing is concerned, they want to be absolutely sure they have thought of everything - and asked me to build this. And that's when it hit me luck a brick that this wont work well if its going out to a strat2 and syncing, LOL.
Any additional thoughts? Michael
===================================
Cleveland Clinic is ranked one of the top 3 hospitals in America by U.S.News & World Report. Visit us online at http://www.clevelandclinic.org for a complete listing of our services, staff and locations.
Confidentiality Note: This message is intended for use only by the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and destroy the material in its entirety, whether electronic or hard copy. Thank you.
Weiner, Michael wrote:
Yes that's helpful. So is there no way I can say have a windows box connect to this server and pull its time successfully even though the ntp server is an hour behind, or say we roll the date forward to March 11, 2007? You can see where we are going with this as far as testing is concerned, they want to be absolutely sure they have thought of everything - and asked me to build this. And that's when it hit me luck a brick that this wont work well if its going out to a strat2 and syncing, LOL.
I haven't tried this, but I'd expect that if you set the 'fudge' entry in /etc/ntp.conf to a low enough number and change the restrictive permissions to allow queries, you could get other machines to sync against your local adjusted clock.
-- Les Mikesell lesmikesell@gmail.com
On Tue, 2007-02-27 at 12:26 -0500, Weiner, Michael wrote:
So is there no way I can say have a windows box connect to this server and pull its time successfully even though the ntp server is an hour behind, or say we roll the date forward to March 11, 2007? You can see where we are going with this as far as testing is concerned, they want to be absolutely sure they have thought of everything - and asked me to build this.
But the NTP server serves out GMT/UTC/UCT (whatever you call it, these days), *it* doesn't change. Daylight savings, or not, your NTP server clocks out the same time. It's the clients making use of it that change their own behavior regarding DST. Whether that be the machine itself (which works its own local time out, but the NTP server doesn't make use of that), or external clients.
"Weiner, Michael" weinerm@ccf.org writes:
What I am trying to do actually is build an authoritative or reference time server that we can use here for testing daylight saving time adjustments in our environment.
Using ntp to test future daylight savings time transitions seems like an awfully round-about way to do it. First of all, ntp tries really hard (too hard if you ask me) to never set a bad time. All your clients under test would have to be tested by restarting ntpd with the -g option every time you wanted to jump the time back to before the transition. If you are going to go to all that trouble, you might as well not run ntpd and just type "date <time-and-date>" and reset the time by hand.
The other problem is that the stock Linux kernel doesn't talk to reference clocks. It needs some patches to do the PPS (Pulse Per Second) protocol that reference clocks use to indicate the precise top of the second.
(As someone else mentioned, you can still use the phony "local" refclock to have your server pretend it still has a valid time. In that case just set the time on your server to be the time under test, restart ntpd and then restart the ntpd's on the clients under test remembering to use the "-g" flag.)
Q: anyone know why the PPS patches never seem to make it into the real kernel sources?
-wolfgang
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Les Mikesell -
Mark Haney -
Tim -
Weiner, Michael -
Wolfgang S. Rupprecht