ntp stratum - NTP

This is a discussion on ntp stratum - NTP ; Hello I own a ubuntu 8.04 server, which provide a ntp service (not only, but it's the thing we look at here...). I would like to know how I can tell the server he is in stratum 3. This is ...

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  1. ntp stratum

    Hello

    I own a ubuntu 8.04 server, which provide a ntp service (not only, but
    it's the thing we look at here...).

    I would like to know how I can tell the server he is in stratum 3.

    This is my /etc/ntp.conf :

    # /etc/ntp.conf, configuration for ntpd
    logfile /var/log/ntp

    #driftfile /var/lib/ntp/ntp.drift
    statsdir /var/log/ntpstats/

    statistics loopstats peerstats clockstats
    filegen loopstats file loopstats type day enable
    filegen peerstats file peerstats type day enable
    filegen clockstats file clockstats type day enable

    # You do need to talk to an NTP server or two (or three).
    #server ntp.your-provider.example

    # pool.ntp.org maps to more than 300 low-stratum NTP servers.
    # Your server will pick a different set every time it starts up.
    # *** Please consider joining the pool! ***
    # *** ***
    server ntp2.jussieu.fr
    server ntp.metas.ch
    server soleil.uvsq.fr
    server ntp.u-psud.fr
    server ntp.obspm.fr
    server ntp1.fau.de
    server audaxsystems.co.uk

    thanks for your answers.
    sincerly yours
    --
    Utilisant le client e-mail révolutionnaire d'Opera :
    http://www.opera.com/mail/

  2. Re: ntp stratum

    stephaneguedon wrote:
    >
    > I would like to know how I can tell the server he is in stratum 3.


    You can't. Why would you want to?

    Your server's stratum will never be less than one greater than the
    numerically lowest stratum amongst its severs, so by choosing servers
    that never have a stratum numerically less than two, yours will never
    have stratum numerically less than 3.

    You can also provide it with a direct connection to a reference clock,
    and force the stratum of that reference clock to be two. However, if
    the clock is good, it is not sensible to give it an artificially bad
    stratum.

    >
    > This is my /etc/ntp.conf :


    [With no reference clocks.]

  3. Re: ntp stratum

    Le Sat, 27 Sep 2008 12:39:13 +0200, David Woolley
    a écrit:

    > stephaneguedon wrote:
    >> I would like to know how I can tell the server he is in stratum 3.

    >
    > You can't. Why would you want to?
    >
    > Your server's stratum will never be less than one greater than the
    > numerically lowest stratum amongst its severs, so by choosing servers
    > that never have a stratum numerically less than two, yours will never
    > have stratum numerically less than 3.
    >
    > You can also provide it with a direct connection to a reference clock,
    > and force the stratum of that reference clock to be two. However, if
    > the clock is good, it is not sensible to give it an artificially bad
    > stratum.
    >
    >> This is my /etc/ntp.conf :

    >
    > [With no reference clocks.]


    The stratum is really 3 !

    but when I run ntpdate from my computer (not the server himself), I get
    strange answer... Like :

    server 192.168.0.2, stratum 16, offset -0.542495, delay 0.02582
    27 Sep 13:24:57 ntpdate[14545]: step time server 192.168.0.2 offset
    -0.542495 sec


    --
    Utilisant le client e-mail révolutionnaire d'Opera :
    http://www.opera.com/mail/

  4. Re: ntp stratum

    stephaneguedon wrote:
    []
    > The stratum is really 3 !


    How do you know that? It depends on what stratum the servers you are sync
    from claim to be.

    > but when I run ntpdate from my computer (not the server himself), I
    > get strange answer... Like :
    >
    > server 192.168.0.2, stratum 16, offset -0.542495, delay 0.02582
    > 27 Sep 13:24:57 ntpdate[14545]: step time server 192.168.0.2 offset
    > -0.542495 sec


    ntpq -p is helpful to see what servers you are actually syncing to. Show
    us the output from this command. A "*" in the first column shows the
    server your system is currently syncing from, and a "reach" value of "0"
    means you are not connecting to a particular server.

    David



  5. Re: ntp stratum

    Le Sat, 27 Sep 2008 13:35:14 +0200, David J Taylor
    a écrit:

    > stephaneguedon wrote:
    > []
    >> The stratum is really 3 !

    >
    > How do you know that? It depends on what stratum the servers you are
    > sync
    > from claim to be.
    >
    >> but when I run ntpdate from my computer (not the server himself), I
    >> get strange answer... Like :
    >>
    >> server 192.168.0.2, stratum 16, offset -0.542495, delay 0.02582
    >> 27 Sep 13:24:57 ntpdate[14545]: step time server 192.168.0.2 offset
    >> -0.542495 sec

    >
    > ntpq -p is helpful to see what servers you are actually syncing to. Show
    > us the output from this command. A "*" in the first column shows the
    > server your system is currently syncing from, and a "reach" value of "0"
    > means you are not connecting to a particular server.
    >
    > David
    >
    >


    thanks for helping me...

    remote refid st t when poll reach delay offset
    jitter
    ================================================== ============================
    +horlogegps.rese 195.220.94.163 2 u 20 64 377 34.027 -19.190
    0.328
    -metasweb01.admi 162.23.3.171 3 u 35 64 377 52.594 -15.991
    0.545
    -soleil.uvsq.fr 193.49.205.19 2 u 29 64 377 33.636 -18.620
    0.387
    *ntp.u-psud.fr 193.49.205.17 2 u 41 64 377 33.756 -20.939
    0.684
    +syrte8.obspm.fr 195.220.94.163 2 u 46 64 377 34.196 -20.969
    0.563
    ntp1-rz.rrze.un .INIT. 16 u - 1024 0 0.000 0.000
    0.000

    the list of servers is in the end of the ntp.conf I posted the first time

    I don't know where come from the ntpl-rz.rrze.un

    --
    Utilisant le client e-mail révolutionnaire d'Opera :
    http://www.opera.com/mail/

  6. Re: ntp stratum

    Le Sat, 27 Sep 2008 14:06:39 +0200, stephaneguedon
    a écrit:

    > Le Sat, 27 Sep 2008 13:35:14 +0200, David J Taylor
    > a écrit:
    >
    >> stephaneguedon wrote:
    >> []
    >>> The stratum is really 3 !

    >>
    >> How do you know that? It depends on what stratum the servers you are
    >> sync
    >> from claim to be.
    >>
    >>> but when I run ntpdate from my computer (not the server himself), I
    >>> get strange answer... Like :
    >>>
    >>> server 192.168.0.2, stratum 16, offset -0.542495, delay 0.02582
    >>> 27 Sep 13:24:57 ntpdate[14545]: step time server 192.168.0.2 offset
    >>> -0.542495 sec

    >>
    >> ntpq -p is helpful to see what servers you are actually syncing to.
    >> Show
    >> us the output from this command. A "*" in the first column shows the
    >> server your system is currently syncing from, and a "reach" value of "0"
    >> means you are not connecting to a particular server.
    >>
    >> David
    >>
    >>

    >
    > thanks for helping me...
    >
    > remote refid st t when poll reach delay offset
    > jitter
    > ================================================== ============================
    > +horlogegps.rese 195.220.94.163 2 u 20 64 377 34.027 -19.190
    > 0.328
    > -metasweb01.admi 162.23.3.171 3 u 35 64 377 52.594 -15.991
    > 0.545
    > -soleil.uvsq.fr 193.49.205.19 2 u 29 64 377 33.636 -18.620
    > 0.387
    > *ntp.u-psud.fr 193.49.205.17 2 u 41 64 377 33.756 -20.939
    > 0.684
    > +syrte8.obspm.fr 195.220.94.163 2 u 46 64 377 34.196 -20.969
    > 0.563
    > ntp1-rz.rrze.un .INIT. 16 u - 1024 0 0.000
    > 0.000 0.000
    >
    > the list of servers is in the end of the ntp.conf I posted the first time
    >
    > I don't know where come from the ntpl-rz.rrze.un
    >


    sorry... I know I am in stratum 3, because all servers I use are at least
    in stratum 2 (refer to the list from the cru for example).

    --
    Utilisant le client e-mail révolutionnaire d'Opera :
    http://www.opera.com/mail/

  7. Re: ntp stratum

    stephaneguedon wrote:

    >
    > server 192.168.0.2, stratum 16, offset -0.542495, delay 0.02582
    > 27 Sep 13:24:57 ntpdate[14545]: step time server 192.168.0.2 offset
    > -0.542495 sec


    This indicates that the server isn't synchronised. Your ntpq output
    suggests otherwise. Could the two measurements have been done at
    different times? Do you still get stratum 16 on ntpdate when ntpq is
    showing a *?

  8. Re: ntp stratum

    stephaneguedon wrote:
    []
    > sorry... I know I am in stratum 3, because all servers I use are at
    > least in stratum 2 (refer to the list from the cru for example).


    No. you don't. You /hope/ and /expect/ that you will be at stratum 3,
    because you /hope/ that all the servers you sync to will be at stratum 2.
    It may be that you loose connection to the servers, and then you would not
    be stratum 3, or in the unlikely event that all your connected servers go
    a higher stratum.

    I appreciate that you are trying to be at stratum 3, so I am being a
    little pedantic.

    Cheers,
    David



  9. Re: ntp stratum

    stephaneguedon wrote:
    []
    > thanks for helping me...
    >
    > remote refid st t when poll reach delay offset
    > jitter
    > ================================================== ============================
    > +horlogegps.rese 195.220.94.163 2 u 20 64 377 34.027 -19.190
    > 0.328
    > -metasweb01.admi 162.23.3.171 3 u 35 64 377 52.594 -15.991
    > 0.545
    > -soleil.uvsq.fr 193.49.205.19 2 u 29 64 377 33.636 -18.620
    > 0.387
    > *ntp.u-psud.fr 193.49.205.17 2 u 41 64 377 33.756 -20.939
    > 0.684
    > +syrte8.obspm.fr 195.220.94.163 2 u 46 64 377 34.196 -20.969
    > 0.563
    > ntp1-rz.rrze.un .INIT. 16 u - 1024 0 0.000 0.000
    > 0.000
    >
    > the list of servers is in the end of the ntp.conf I posted the first
    > time
    > I don't know where come from the ntpl-rz.rrze.un


    The "*" against ntp.u-psud.fr shows that you are synced to a stratum 2
    server, so you will be at stratum 3. The command:

    ntpq -c rv

    should confirm that. Please note that it can take a minute or two from
    when you start NTP for a synchronised state to be established.

    Cheers,
    David



  10. Re: ntp stratum

    Le Sat, 27 Sep 2008 14:23:40 +0200, David J Taylor
    a écrit:

    > stephaneguedon wrote:
    > []
    >> thanks for helping me...
    >>
    >> remote refid st t when poll reach delay offset
    >> jitter
    >> ================================================== ============================
    >> +horlogegps.rese 195.220.94.163 2 u 20 64 377 34.027 -19.190
    >> 0.328
    >> -metasweb01.admi 162.23.3.171 3 u 35 64 377 52.594 -15.991
    >> 0.545
    >> -soleil.uvsq.fr 193.49.205.19 2 u 29 64 377 33.636 -18.620
    >> 0.387
    >> *ntp.u-psud.fr 193.49.205.17 2 u 41 64 377 33.756 -20.939
    >> 0.684
    >> +syrte8.obspm.fr 195.220.94.163 2 u 46 64 377 34.196 -20.969
    >> 0.563
    >> ntp1-rz.rrze.un .INIT. 16 u - 1024 0 0.000 0.000
    >> 0.000
    >>
    >> the list of servers is in the end of the ntp.conf I posted the first
    >> time
    >> I don't know where come from the ntpl-rz.rrze.un

    >
    > The "*" against ntp.u-psud.fr shows that you are synced to a stratum 2
    > server, so you will be at stratum 3. The command:
    >
    > ntpq -c rv
    >
    > should confirm that. Please note that it can take a minute or two from
    > when you start NTP for a synchronised state to be established.
    >
    > Cheers,
    > David
    >
    >


    it seems to be ok currently...

    the stratum said 3 on the server and on the client too !
    It's strange. I hope it will continue on this way a long time.

    thanks

    --
    Utilisant le client e-mail révolutionnaire d'Opera :
    http://www.opera.com/mail/

  11. Re: ntp stratum

    stephaneguedon wrote:
    > Hello
    >
    > I own a ubuntu 8.04 server, which provide a ntp service (not only, but
    > it's the thing we look at here...).
    >
    > I would like to know how I can tell the server he is in stratum 3.
    >
    > This is my /etc/ntp.conf :
    >
    > # /etc/ntp.conf, configuration for ntpd
    > logfile /var/log/ntp
    >
    > #driftfile /var/lib/ntp/ntp.drift
    > statsdir /var/log/ntpstats/
    >
    > statistics loopstats peerstats clockstats
    > filegen loopstats file loopstats type day enable
    > filegen peerstats file peerstats type day enable
    > filegen clockstats file clockstats type day enable
    >
    > # You do need to talk to an NTP server or two (or three).
    > #server ntp.your-provider.example
    >
    > # pool.ntp.org maps to more than 300 low-stratum NTP servers.
    > # Your server will pick a different set every time it starts up.
    > # *** Please consider joining the pool! ***
    > # *** ***
    > server ntp2.jussieu.fr
    > server ntp.metas.ch
    > server soleil.uvsq.fr
    > server ntp.u-psud.fr
    > server ntp.obspm.fr
    > server ntp1.fau.de
    > server audaxsystems.co.uk
    >
    > thanks for your answers.
    > sincerly yours


    Ntpd will compute the proper stratum! It simply adds 1 to the stratum of
    the source it is using. If ntpd is synchronized with a stratum 1 source
    it will declare itself stratum 2. If synchronized to a stratum 2 source
    it will declare stratum 3, etc. In principle, you could get down to
    stratum 15 but if you do something is probably VERY wrong. The stratum
    is simply the number of "hops" from the atomic clock at the root.
    Stratum 1 got it from atomic clock, stratum 2 got it from a stratum 1
    server, stratum 3 go its time from a stratum 2 server and so on.

    If you are using the unsynchronized local clock as a clock of last
    resort it is customary to force a stratum of 10 to ensure that nobody
    will believe that clock if he can possibly find anything at a lower
    stratum number.

    Stratum has nothing whatever to do with accuracy. ISTR that the latest
    NTP server survey found a clock claiming stratum 1 that did not even
    have the correct year!!!!

  12. Re: ntp stratum

    On 2008-09-27, David J Taylor wrote:

    > Please note that it can take a minute or two from when you start NTP
    > for a synchronised state to be established.


    Initial synchronization takes approximately 4 to 5 minutes when 'iburst'
    is not used on the server lines.

    Initial synchronization with 'iburst' can take as little as 10 to 20
    seconds.

    --
    Steve Kostecke
    NTP Public Services Project - http://support.ntp.org/

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