NTP on LAN - NTP

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Thread: NTP on LAN

  1. NTP on LAN

    I'm totally new to NTP. Please excuse any noob questions. What I want
    is this...

    I have 2 computers connected on the same lan. I want one of them to be
    set up as a NTP server and the other to be setup as a NTP client. This
    is my initial goal. I tried giving the ip address of the server in the
    client's /etc/ntp.conf file and i gave localhost(127.0.0.1) in the
    servers /etc/ntp.conf file. After this how do i go about checking if
    they're even getting synchronized or anything at all? Also some links
    for learning more would also be appreciated.
    OS: Ubuntu Hardy Heron on both server and client.
    Thanks in advance.

  2. Re: NTP on LAN

    05IT042 writes:

    >I'm totally new to NTP. Please excuse any noob questions. What I want
    >is this...


    >I have 2 computers connected on the same lan. I want one of them to be
    >set up as a NTP server and the other to be setup as a NTP client. This
    >is my initial goal. I tried giving the ip address of the server in the
    >client's /etc/ntp.conf file and i gave localhost(127.0.0.1) in the


    And just what would that do? You are asking your computer to ask itself
    what the time is and to adjust its own clock so it shows the same time as
    it does itself. You need to find a computer or a system that has a better
    of idea of time that the computer does itself. eg pool.ntp.org

    If those two computers are not tied to the rest of the net at all, then the
    LOCAL refclock could be used but again is a bad idea.



    >servers /etc/ntp.conf file. After this how do i go about checking if
    >they're even getting synchronized or anything at all? Also some links


    ntpq -p will show the state of the system and its sources.

    >for learning more would also be appreciated.


    www.ntp.org


    >OS: Ubuntu Hardy Heron on both server and client.
    >Thanks in advance.


  3. Re: NTP on LAN

    05IT042 wrote:
    > I'm totally new to NTP. Please excuse any noob questions. What I want
    > is this...
    >
    > I have 2 computers connected on the same lan. I want one of them to be
    > set up as a NTP server and the other to be setup as a NTP client. This
    > is my initial goal. I tried giving the ip address of the server in the
    > client's /etc/ntp.conf file and i gave localhost(127.0.0.1) in the
    > servers /etc/ntp.conf file. After this how do i go about checking if
    > they're even getting synchronized or anything at all? Also some links
    > for learning more would also be appreciated.
    > OS: Ubuntu Hardy Heron on both server and client.
    > Thanks in advance.


    Are you trying to synchronize these computers with each other? Or are
    you trying to synchronize them to an external server or clock?

    If you don't really care what time it is but just want all the machines
    to have the SAME time, there is something called "orphan mode" which
    will allow you to do that. (I've never used it or wanted to!)

    The more conventional way to use NTP is to synchronize to a group of
    external servers or to a hardware reference clock; e.g. a GPS timing
    receiver or a WWV/WWVH/WWVB/CHU/JJY/etc receiver. (These are all
    shortwave radio staions operated bye the US Government, the Canadian
    government, or the Japanese government. Other countries operate such
    time broadcasts but I'm not familiar with the details.

    There are lists of Stratum 1 and Stratum 2 servers at
    http://www.ntp.org/ where you will also find links to documentation,
    source code, and other useful stuff.

  4. Re: NTP on LAN

    On 2008-09-18, 05IT042 wrote:

    > I have 2 computers connected on the same lan. I want one of them to be
    > set up as a NTP server and the other to be setup as a NTP client. This
    > is my initial goal. I tried giving the ip address of the server in the
    > client's /etc/ntp.conf file


    The ntp.conf on the "client" should, at a minimum, consist of:

    driftfile /path/to/ntp.drift
    server


    Replace "/path/to/ntp.drift" with a full path + filename to a
    location which is writable ny the ntp user. A typical location is
    "/var/lib/ntp/ntp.drift".

    > and i gave localhost(127.0.0.1) in the servers /etc/ntp.conf file.


    This will not do what you think it will do.

    If you have no real time sources (i.e. remote time servers or locally
    attached ref-clocks) available you may use the Undisciplined Local
    Clock (or LocalCLK or LOCAL) or Orphan Mode.

    The LocalCLK and Orphan Mode merely allow ntpd to claim to synchronized
    to _something_ and serve time to others. They do not make the time
    correct. Nor do they control any drift or make your clock tick at the
    correct rate.

    If at all possible you should provide a sufficient number of real time
    sources to ntpd.

    If your application is not critical you may wish to use the NTP Pool
    (see http://support.ntp.org/pool and http://www.pool.ntp.org/). The
    mininal configuration for a server using the pool is:

    driftfile /path/to/ntp.drift
    I server 0.pool.ntp.org iburst
    server 1.pool.ntp.org iburst
    server 2.pool.ntp.org iburst
    server pool.ntp.org

    To use the just Undisciplined Local Clock the minimal configuration is:

    driftfile /path/to/ntp.drift
    server 127.127.1.0
    fudge 127.127.1.0 stratum 10

    To use just Orphan Mode the minimal configuration is:

    driftfile /path/to/ntp.drift
    tos orphan 10

    You may add the 127.127.1.x lines or the orphan line to an ntp.conf
    in addition to remote time servers. Orphan Mode is preferred if your
    version of NTP supports it.

    > After this how do i go about checking if
    > they're even getting synchronized or anything at all?


    > Also some links for learning more would also be appreciated.


    The NTP home-page is http://www.ntp.org/

    The NTP Public Services Project home-page is http://support.ntp.org/

    Documentation indices are available at
    http://www.ntp.org/documentation.html and http://support.ntp.org/doc

    Documentation for the NTP Development release series is located at
    http://www.eecis.udel.edu/~mills/ntp/html/

    Documentation for NTP Stable releases is included in the ./html/
    directory in the Distribution and is archived at http://doc.ntp.org/

    > OS: Ubuntu Hardy Heron on both server and client.


    What version of NTP are you using?

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

  5. Re: NTP on LAN

    On Sep 18, 10:24*pm, Steve Kostecke wrote:
    > On 2008-09-18, 05IT042 wrote:
    >
    > > I have 2 computers connected on the same lan. I want one of them to be
    > > set up as a NTP server and the other to be setup as a NTP client. This
    > > is my initial goal. I tried giving the ip address of the server in the
    > > client's /etc/ntp.conf file

    >
    > The ntp.conf on the "client" should, at a minimum, consist of:
    >
    > * * * * driftfile /path/to/ntp.drift
    > * * * * server

    >
    > Replace "/path/to/ntp.drift" with a full path + filename to a
    > location which is writable ny the ntp user. A typical location is
    > "/var/lib/ntp/ntp.drift".
    >
    > > and i gave localhost(127.0.0.1) in the servers /etc/ntp.conf file.

    >
    > This will not do what you think it will do.
    >
    > If you have no real time sources (i.e. remote time servers or locally
    > attached ref-clocks) available you may use the Undisciplined Local
    > Clock (or LocalCLK or LOCAL) or Orphan Mode.
    >
    > The LocalCLK and Orphan Mode merely allow ntpd to claim to synchronized
    > to _something_ and serve time to others. They do not make the time
    > correct. Nor do they control any drift or make your clock tick at the
    > correct rate.
    >
    > If at all possible you should provide a sufficient number of real time
    > sources to ntpd.
    >
    > If your application is not critical you may wish to use the NTP Pool
    > (seehttp://support.ntp.org/poolandhttp://www.pool.ntp.org/). The
    > mininal configuration for a server using the pool is:
    >
    > * * * * driftfile /path/to/ntp.drift
    > I * * * server 0.pool.ntp.org iburst
    > * * * * server 1.pool.ntp.org iburst
    > * * * * server 2.pool.ntp.org iburst
    > * * * * server pool.ntp.org
    >
    > To use the just Undisciplined Local Clock the minimal configuration is:
    >
    > * * * * driftfile /path/to/ntp.drift
    > * * * * server 127.127.1.0
    > * * * * fudge 127.127.1.0 stratum 10
    >
    > To use just Orphan Mode the minimal configuration is:
    >
    > * * * * driftfile /path/to/ntp.drift
    > * * * * tos orphan 10
    >
    > You may add the 127.127.1.x lines or the orphan line to an ntp.conf
    > in addition to remote time servers. Orphan Mode is preferred if your
    > version of NTP supports it.
    >
    > > After this how do i go about checking if
    > > they're even getting synchronized or anything at all?
    > > Also some links for learning more would also be appreciated.

    >
    > The NTP home-page ishttp://www.ntp.org/
    >
    > The NTP Public Services Project home-page ishttp://support.ntp.org/
    >
    > Documentation indices are available athttp://www.ntp.org/documentation.htmlandhttp://support.ntp.org/doc
    >
    > Documentation for the NTP Development release series is located athttp://www.eecis.udel.edu/~mills/ntp/html/
    >
    > Documentation for NTP Stable releases is included in the ./html/
    > directory in the Distribution and is archived athttp://doc.ntp.org/
    >
    > > OS: Ubuntu Hardy Heron on both server and client.

    >
    > What version of NTP are you using?
    >
    > --
    > Steve Kostecke
    > NTP Public Services Project -http://support.ntp.org/


    Okay, i wanted 2 computers on a lan. One as the ntp server and the
    other as the client. I want the client to synchronize to the server.
    If i understand right, i have to use orphan mode on my server and what
    on my client?

  6. Re: NTP on LAN

    05IT042 writes:

    >On Sep 18, 10:24=A0pm, Steve Kostecke wrote:
    >> On 2008-09-18, 05IT042 wrote:
    >>
    >> > I have 2 computers connected on the same lan. I want one of them to be
    >> > set up as a NTP server and the other to be setup as a NTP client. This
    >> > is my initial goal. I tried giving the ip address of the server in the
    >> > client's /etc/ntp.conf file

    >>
    >> The ntp.conf on the "client" should, at a minimum, consist of:
    >>
    >> =A0 =A0 =A0 =A0 driftfile /path/to/ntp.drift
    >> =A0 =A0 =A0 =A0 server

    >>
    >> Replace "/path/to/ntp.drift" with a full path + filename to a
    >> location which is writable ny the ntp user. A typical location is
    >> "/var/lib/ntp/ntp.drift".
    >>
    >> > and i gave localhost(127.0.0.1) in the servers /etc/ntp.conf file.

    >>
    >> This will not do what you think it will do.
    >>
    >> If you have no real time sources (i.e. remote time servers or locally
    >> attached ref-clocks) available you may use the Undisciplined Local
    >> Clock (or LocalCLK or LOCAL) or Orphan Mode.
    >>
    >> The LocalCLK and Orphan Mode merely allow ntpd to claim to synchronized
    >> to _something_ and serve time to others. They do not make the time
    >> correct. Nor do they control any drift or make your clock tick at the
    >> correct rate.
    >>
    >> If at all possible you should provide a sufficient number of real time
    >> sources to ntpd.
    >>
    >> If your application is not critical you may wish to use the NTP Pool
    >> (seehttp://support.ntp.org/poolandhttp://www.pool.ntp.org/). The
    >> mininal configuration for a server using the pool is:
    >>
    >> =A0 =A0 =A0 =A0 driftfile /path/to/ntp.drift
    >> I =A0 =A0 =A0 server 0.pool.ntp.org iburst
    >> =A0 =A0 =A0 =A0 server 1.pool.ntp.org iburst
    >> =A0 =A0 =A0 =A0 server 2.pool.ntp.org iburst
    >> =A0 =A0 =A0 =A0 server pool.ntp.org
    >>
    >> To use the just Undisciplined Local Clock the minimal configuration is:
    >>
    >> =A0 =A0 =A0 =A0 driftfile /path/to/ntp.drift
    >> =A0 =A0 =A0 =A0 server 127.127.1.0
    >> =A0 =A0 =A0 =A0 fudge 127.127.1.0 stratum 10
    >>
    >> To use just Orphan Mode the minimal configuration is:
    >>
    >> =A0 =A0 =A0 =A0 driftfile /path/to/ntp.drift
    >> =A0 =A0 =A0 =A0 tos orphan 10
    >>
    >> You may add the 127.127.1.x lines or the orphan line to an ntp.conf
    >> in addition to remote time servers. Orphan Mode is preferred if your
    >> version of NTP supports it.
    >>
    >> > After this how do i go about checking if
    >> > they're even getting synchronized or anything at all?
    >> > Also some links for learning more would also be appreciated.

    >>
    >> The NTP home-page ishttp://www.ntp.org/
    >>
    >> The NTP Public Services Project home-page ishttp://support.ntp.org/
    >>
    >> Documentation indices are available athttp://www.ntp.org/documentation.ht=

    >mlandhttp://support.ntp.org/doc
    >>
    >> Documentation for the NTP Development release series is located athttp://=

    >www.eecis.udel.edu/~mills/ntp/html/
    >>
    >> Documentation for NTP Stable releases is included in the ./html/
    >> directory in the Distribution and is archived athttp://doc.ntp.org/
    >>
    >> > OS: Ubuntu Hardy Heron on both server and client.

    >>
    >> What version of NTP are you using?
    >>
    >> --
    >> Steve Kostecke
    >> NTP Public Services Project -http://support.ntp.org/


    >Okay, i wanted 2 computers on a lan. One as the ntp server and the
    >other as the client. I want the client to synchronize to the server.
    >If i understand right, i have to use orphan mode on my server and what
    >on my client?


    Is that lan a completely private lan with no connection to the outside
    world? If it has a connection to the outside, use ntp properly and have
    your server at least use some outside thing to configure to. If it really a
    totally issolated lan, then make the server orphaned, and the client just
    acts like a client, using the server as it time source.


  7. Re: NTP on LAN

    On 2008-09-19, 05IT042 wrote:

    > On Sep 18, 10:24*pm, Steve Kostecke wrote:
    >
    >> What version of NTP are you using?

    >
    > Okay, i wanted 2 computers on a lan. One as the ntp server and the
    > other as the client.


    Does this network have external connectivity? Do you really need to
    operate a "time island"?

    > I want the client to synchronize to the server.


    If you don't provide the ntpd with a stable time source, or spend some
    time tuning the system which will be your "server", the best you can
    hope for is that the "client" will be chasing a moving "server".

    > If i understand right, i have to use orphan mode on my server and what
    > on my client?


    Choose one system to be your "server" and configure it to use either
    the Undisciplined Local Clock (127.127.0.x) or Orphan Mode (as shown in
    the examples in my previous article).


    # server at 192.189.19.1
    driftfile /var/lib/ntp/ntp.drift
    server 127.127.1.0 minpoll 4
    fudge 127.127.1.0 stratum 10

    or

    # server at 192.189.19.1
    driftfile /var/lib/ntp/ntp.drift
    tos orphan 10

    Configure the other system to poll your "server" (as shown in the
    examples in my previous article).

    # client at 192.168.19.2
    driftfile /var/lib/ntp/ntp.drift
    server 192.168.19.1 iburst

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

  8. Re: NTP on LAN

    05IT042 wrote:

    >
    > Okay, i wanted 2 computers on a lan. One as the ntp server and the
    > other as the client. I want the client to synchronize to the server.
    > If i understand right, i have to use orphan mode on my server and what
    > on my client?


    With orphan mode, all machines are configured the same, and the system
    choses the master for itself. It's more useful when there are rather
    more than two machines. You should not use it if one machine should
    always be master.

  9. Re: NTP on LAN

    On 2008-09-19, David Woolley wrote:
    > 05IT042 wrote:
    >
    >> Okay, i wanted 2 computers on a lan. One as the ntp server and the
    >> other as the client. I want the client to synchronize to the server.
    >> If i understand right, i have to use orphan mode on my server and what
    >> on my client?

    >
    > With orphan mode, all machines are configured the same, and the system
    > choses the master for itself. It's more useful when there are rather
    > more than two machines. You should not use it if one machine should
    > always be master.


    Nonsense.

    A single ntpd can be configured in Orphan Mode to serve as the "server"
    for a time island.

    A hierarchy of Orphan Mode servers can be establish by properly setting
    the strata on the tos orphan lines.

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

  10. Re: NTP on LAN

    On Sep 19, 8:31*pm, Steve Kostecke wrote:
    > On 2008-09-19, 05IT042 wrote:
    >
    > > On Sep 18, 10:24*pm, Steve Kostecke wrote:

    >
    > >> What version of NTP are you using?

    >
    > > Okay, i wanted 2 computers on a lan. One as the ntp server and the
    > > other as the client.

    >
    > Does this network have external connectivity? Do you really need to
    > operate a "time island"?
    >
    > > I want the client to synchronize to the server.

    >
    > If you don't provide the ntpd with a stable time source, or spend some
    > time tuning the system which will be your "server", the best you can
    > hope for is that the "client" will be chasing a moving "server".
    >
    > > If i understand right, i have to use orphan mode on my server and what
    > > on my client?

    >
    > Choose one system to be your "server" and configure it to use either
    > the Undisciplined Local Clock (127.127.0.x) or Orphan Mode (as shown in
    > the examples in my previous article).
    >
    > * * * * # server at 192.189.19.1
    > * * * * driftfile /var/lib/ntp/ntp.drift
    > * * * * server 127.127.1.0 minpoll 4
    > * * * * fudge 127.127.1.0 stratum 10
    >
    > or
    >
    > * * * * # server at 192.189.19.1
    > * * * * driftfile /var/lib/ntp/ntp.drift
    > * * * * tos orphan 10
    >
    > Configure the other system to poll your "server" (as shown in the
    > examples in my previous article).
    >
    > * * * * # client at 192.168.19.2
    > * * * * driftfile /var/lib/ntp/ntp.drift
    > * * * * server 192.168.19.1 iburst
    >
    > --
    > Steve Kostecke
    > NTP Public Services Project -http://support.ntp.org/


    Did exactly as above. I'm using 4.2.4p5. Now how do i verify that the
    client is getting synchronized with the server? And yeah I am on a lan
    which connects to the internet. But, i'm trying this for a different
    purpose altogther

  11. Re: NTP on LAN

    >>> In article , 05IT042 writes:

    raghuramos1987> I'm using 4.2.4p5. Now how do i verify that the client is
    raghuramos1987> getting synchronized with the server? And yeah I am on a lan
    raghuramos1987> which connects to the internet. But, i'm trying this for a
    raghuramos1987> different purpose altogther

    See http://support.ntp.org/bin/view/Supp...ControllingNTP

    --
    Harlan Stenn
    http://ntpforum.isc.org - be a member!

  12. Re: NTP on LAN

    On 2008-09-21, 05IT042 wrote:
    > On Sep 19, 8:31*pm, Steve Kostecke wrote:
    >
    > [---=| Quote block shrinked by t-prot: 36 lines snipped |=---]
    >
    >> Configure the other system to poll your "server" (as shown in the
    >> examples in my previous article).
    >>
    >> # client at 192.168.19.2
    >> driftfile /var/lib/ntp/ntp.drift
    >> server 192.168.19.1 iburst

    >
    > Did exactly as above. I'm using 4.2.4p5. Now how do i verify that the
    > client is getting synchronized with the server?


    'ntpq -p' on the client will show you that ntpd's peer billboard.
    Increasing numbers in the reach column indicate that this ntd is
    succesfully polling the server(s). A "*" in the left column marks the
    server that has been chosen as the "sys_peer".

    'ntpq -crv' on the client will show you that ntpd's variables.

    > And yeah I am on a lan which connects to the internet. But, i'm trying
    > this for a different purpose altogther


    What are you trying to demonstrate?

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

  13. Re: NTP on LAN

    05IT042 writes:

    >On Sep 19, 8:31=A0pm, Steve Kostecke wrote:
    >> On 2008-09-19, 05IT042 wrote:
    >>
    >> > On Sep 18, 10:24=A0pm, Steve Kostecke wrote:

    >>
    >> >> What version of NTP are you using?

    >>
    >> > Okay, i wanted 2 computers on a lan. One as the ntp server and the
    >> > other as the client.

    >>
    >> Does this network have external connectivity? Do you really need to
    >> operate a "time island"?
    >>
    >> > I want the client to synchronize to the server.

    >>
    >> If you don't provide the ntpd with a stable time source, or spend some
    >> time tuning the system which will be your "server", the best you can
    >> hope for is that the "client" will be chasing a moving "server".
    >>
    >> > If i understand right, i have to use orphan mode on my server and what
    >> > on my client?

    >>
    >> Choose one system to be your "server" and configure it to use either
    >> the Undisciplined Local Clock (127.127.0.x) or Orphan Mode (as shown in
    >> the examples in my previous article).
    >>
    >> =A0 =A0 =A0 =A0 # server at 192.189.19.1
    >> =A0 =A0 =A0 =A0 driftfile /var/lib/ntp/ntp.drift
    >> =A0 =A0 =A0 =A0 server 127.127.1.0 minpoll 4
    >> =A0 =A0 =A0 =A0 fudge 127.127.1.0 stratum 10
    >>
    >> or
    >>
    >> =A0 =A0 =A0 =A0 # server at 192.189.19.1
    >> =A0 =A0 =A0 =A0 driftfile /var/lib/ntp/ntp.drift
    >> =A0 =A0 =A0 =A0 tos orphan 10
    >>
    >> Configure the other system to poll your "server" (as shown in the
    >> examples in my previous article).
    >>
    >> =A0 =A0 =A0 =A0 # client at 192.168.19.2
    >> =A0 =A0 =A0 =A0 driftfile /var/lib/ntp/ntp.drift
    >> =A0 =A0 =A0 =A0 server 192.168.19.1 iburst
    >>
    >> --
    >> Steve Kostecke
    >> NTP Public Services Project -http://support.ntp.org/


    >Did exactly as above. I'm using 4.2.4p5. Now how do i verify that the
    >client is getting synchronized with the server? And yeah I am on a lan
    >which connects to the internet. But, i'm trying this for a different
    >purpose altogther


    On the client do
    ntpq -p
    a while after bootup.
    You should see that it is syncing to the server.



  14. Re: NTP on LAN

    Steve Kostecke wrote:

    >
    > Nonsense.
    >
    > A single ntpd can be configured in Orphan Mode to serve as the "server"
    > for a time island.


    I hadn't considered the degenerate case. However, if one looks at the
    key selling points for orphan mode, in the documentaion, one finds that
    they all depend on having multiple orphans at the same stratum:

    > There are many disadvantages using the local clock driver: multiple
    > source redundancy is not possible and the subnet is vulnerable to
    > single-point failures. Orphan mode is intended to replace the need for


    If it really has benefits in contexts where there is only one orphan
    mode server, the documentation needs amending to mention them.

    Note two orphans at the same stratum aren't possible here, as the
    requirement included a strict precedence and two at different strata is
    another degenerate case.


  15. Re: NTP on LAN

    On 2008-09-28, David Woolley wrote:

    > Steve Kostecke wrote:
    >
    >
    >> Nonsense.
    >>
    >> A single ntpd can be configured in Orphan Mode to serve as the
    >> "server" for a time island.

    >
    > I hadn't considered the degenerate case. However, if one looks at the
    > key selling points for orphan mode, in the documentaion, one finds
    > that they all depend on having multiple orphans at the same stratum:
    >
    >> | There are many disadvantages using the local clock driver:
    >> | multiple source redundancy is not possible and the subnet is
    >> | vulnerable to single-point failures. Orphan mode is intended to
    >> | replace the need for

    >
    > If it really has benefits in contexts where there is only one orphan
    > mode server, the documentation needs amending to mention them.


    The Distribution Documentation is maintained by one person; you'll have
    to contact him about this.

    Anyone who is interested is welcome to contribute to the Community
    Supported Documentation at http://support.ntp.org/support

    > Note two orphans at the same stratum aren't possible here, as the
    > requirement included a strict precedence and two at different strata is
    > another degenerate case.


    It is possible to set the orphan strata to enforce precedence.

    There is no requirement for members of an orphan mode group to operate
    at the same stratum.

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

  16. Re: NTP on LAN

    Steve Kostecke wrote:

    >
    > It is possible to set the orphan strata to enforce precedence.


    But there appears to be no advantage in doing that, when you only have
    one orphan on each stratum. That's why I say it is a degenerate case.

    >
    > There is no requirement for members of an orphan mode group to operate
    > at the same stratum.


    But the key advantages only materialise when you do do so.
    >


  17. Re: NTP on LAN

    David,

    I'm not sure which configuration you are considering; the documentation
    clearly shows, even in the diagrams, that there can be more than one
    orphan server and more than one orphan client. The expressed intent is
    that, should all sources of time be lost, that onlyu all orphan clients
    select the same orphan server. It's as simple as that.

    Orphan mode was motivated by certain misguided configurations that tried
    to engineer failover configurations using engineered local clock stratum
    assignments. These are dangerous, fragile and will form loops unless
    specifically and carefully done. Usually under some failure scenario or
    other a cycle forms between two local clocks and in the best
    Bellman-Ford tradition, they count to infinity.

    Orphan mode was specifically designed for the most common case where a
    LAN has multiple Internet servers and where one or more of them can
    become disconnected. The (single) orphan server becoms the source of
    last resort.

    Dave

    David Woolley wrote:

    > Steve Kostecke wrote:
    >
    >>
    >> Nonsense.
    >>
    >> A single ntpd can be configured in Orphan Mode to serve as the "server"
    >> for a time island.

    >
    >
    > I hadn't considered the degenerate case. However, if one looks at the
    > key selling points for orphan mode, in the documentaion, one finds that
    > they all depend on having multiple orphans at the same stratum:
    >
    >> There are many disadvantages using the local clock driver: multiple
    >> source redundancy is not possible and the subnet is vulnerable to
    >> single-point failures. Orphan mode is intended to replace the need for

    >
    >
    > If it really has benefits in contexts where there is only one orphan
    > mode server, the documentation needs amending to mention them.
    >
    > Note two orphans at the same stratum aren't possible here, as the
    > requirement included a strict precedence and two at different strata is
    > another degenerate case.
    >


  18. Re: NTP on LAN

    Steve,

    May I remind folks that the single definitive documentation source is
    indeed me and the reason for that is very simple. I've taken a great
    deal of trouble, years in fact, to make sure the documentation actually
    does describe how the animal actually works. The fact that the
    definitive documentation is essentially under lock and key is absolutely
    intentional, mainly to avoid inaccuracies that creep in when other OS
    suppilers twitch it for their local customers and get it wrong.

    Informal support documentation is a good thing, especially when it saves
    folks from reading detailed technical material. However, when it comes
    down to real chapter and verse, the definitive documentation comes from
    me. As it says in the documentation, I am happy to receive bug reports,
    typos and even complaints about the lock and key policy. I am also jappy
    to receive and integrate new pages in the document set; I have done that
    several times, but those pages get a careful read and sanity check first.

    Dave

    Steve Kostecke wrote:

    > On 2008-09-28, David Woolley wrote:
    >
    >
    >>Steve Kostecke wrote:
    >>
    >>
    >>
    >>>Nonsense.
    >>>
    >>>A single ntpd can be configured in Orphan Mode to serve as the
    >>>"server" for a time island.

    >>
    >>I hadn't considered the degenerate case. However, if one looks at the
    >>key selling points for orphan mode, in the documentaion, one finds
    >>that they all depend on having multiple orphans at the same stratum:
    >>
    >>
    >>>| There are many disadvantages using the local clock driver:
    >>>| multiple source redundancy is not possible and the subnet is
    >>>| vulnerable to single-point failures. Orphan mode is intended to
    >>>| replace the need for

    >>
    >>If it really has benefits in contexts where there is only one orphan
    >>mode server, the documentation needs amending to mention them.

    >
    >
    > The Distribution Documentation is maintained by one person; you'll have
    > to contact him about this.
    >
    > Anyone who is interested is welcome to contribute to the Community
    > Supported Documentation at http://support.ntp.org/support
    >
    >
    >>Note two orphans at the same stratum aren't possible here, as the
    >>requirement included a strict precedence and two at different strata is
    >>another degenerate case.

    >
    >
    > It is possible to set the orphan strata to enforce precedence.
    >
    > There is no requirement for members of an orphan mode group to operate
    > at the same stratum.
    >


  19. Re: NTP on LAN

    David L. Mills wrote:
    >
    > I'm not sure which configuration you are considering; the documentation
    > clearly shows, even in the diagrams, that there can be more than one


    Steve, rather than I, was proposing a configuration in which there was
    one orphan mode server and one normal client. I have no problem with
    the use of orphan mode with multiple servers at the same orphan level.

    > orphan server and more than one orphan client. The expressed intent is
    > that, should all sources of time be lost, that onlyu all orphan clients
    > select the same orphan server. It's as simple as that.
    >
    > Orphan mode was motivated by certain misguided configurations that tried
    > to engineer failover configurations using engineered local clock stratum
    > assignments. These are dangerous, fragile and will form loops unless


    Steve was talking about engineering a failover precedence arrangement by
    engineering the orphan strata to all be different.

    > specifically and carefully done. Usually under some failure scenario or
    > other a cycle forms between two local clocks and in the best
    > Bellman-Ford tradition, they count to infinity.
    >
    > Orphan mode was specifically designed for the most common case where a
    > LAN has multiple Internet servers and where one or more of them can
    > become disconnected. The (single) orphan server becoms the source of
    > last resort.


    I'm not sure if you mean single in a static or dynamic s sense. The
    documentation indicates benefits when it is a dynamic sense, but doesn't
    seem to indicate any real difference from the local clock solution when
    there is never more than one candidate.

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