[ntp:questions] 3 Peer server at same stratum

RICCARDO castellani.riccardo at tiscali.it
Mon Mar 5 08:57:42 UTC 2007


On 4 Mar, 16:18, "Richard B. gilbert" <rgilber... at comcast.net> wrote:
> Riccardo wrote:
> > Ok, How is't possible that these three peer servers share time information
> > among themselves ?
>
> > For example:
> > Server "A" shall retrieve time information (for example "TI-1") from public
> > server of stratum 1 (ntp1.ien.it),
> > Server "B" shall retrieve time information (for example "TI-2") from public
> > server of stratum 1 (ntp2.fau.de),
> > Server "C" shall retrieve time information (for example "TI-3") from public
> > server of stratum 1 (ptbtime1.ptb.de),
>
> > TI-1, TI-2, TI-3 are three time information which are many similar but they
> > can't being the same time(for few milliseconds), so "two of them" must align
> > with the other in order to share time information, I think.
> > What's logic to select the server (among these 3 peers) which gives reliable
> > time to two others ?
>
> Server "A"  should get time from servers AS1, AS2, AS3 and AS4.  Four
> servers is the minimum for reliability.
>
> Server "B" should get time from BS1, AS2, AS3, and AS4.  (note that one
> server, BS1, is unique.)
>
> Server "C" should get time from AS1, CS2, AS3, and AS4.  Again, one
> server is unique.
>
> Server "D" should get time from AS1, AS2, DS3, and AS4.
>
> Without at least one unique server a peer really has nothing to contribute.
>
> I believe that the peers are then supposed to debate with each other and
> converge to a common time.  See Professor Mills' slides (links athttp://ntp.org/) for the details.



I shall configure my NTP peer servers according to your above
suggestions, but for redundancy do you think that it's necessary to
change stratum level for each peer server(server A,B,C) of my lan ?
(for instance server A stratum 10, server B stratum 11, server C
stratum 12). What do you suggest me ?




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