[ntp:questions] NTP and SNTP in the end, give me precision of 1ms?

Unruh unruh-spam at physics.ubc.ca
Sat Sep 13 19:15:37 UTC 2008


marcelopimentacs at gmail.com (Marcelo Pimenta) writes:

>Hello everybody!

>I am new here and I have a question that envolves NTP and SNTP
>implementations.
>I work with LAN systems and protocols that needs 1milisecond of
>precision(not resolution). I always use a GPS clock like Meinberg with
>Ethernet port to be my NTP/SNTP Server. The clients of this LAN are
>equipments in the same subnetwork and they are SNTP clients. So we have the
>hierarchical system:

>GPS Meinberg Clock - NTP/SNTP Server (Stratum 0?)
> Equipments with SNTP client using the Stratum 0 Server

The GPS is stratum 0. The computer synced to that (ntp server) is stratum 1


>It always worked very well but I want to know if I mix NTP Servers and
>Clients with SNTP client, It will give me precision in the end? Let's

It depends on the quality of your SNTP clients. Some people are incompetent
in writing computer programs. If you have one of their SNTP clients...

There is nothing per se that makes this system impossible to deliver 1ms. 
Of course it depends of where those clients are-- if they are at the bottom
of the sea communicating with 1bd/sec ultralow frequency radio, you will
not get 1ms precision.



>imagine the hierarchical system below:
>GPS Clock - NTP Server (Stratum 0?)
Stratum 1
>Workstation - NTP Client and Server (Stratum 1?)
Stratum 2

>Workstation - NTP/SNTP Client and Server (Stratum 2?)

Stratum 1 if its server is the first line. 

An SNTP canot be a server if it is not tied to a hardware clock.

>Equipments with SNTP client implemented using the Stratum 2 Server.

>The NTP algorithm will give the precision of 1ms in the end, to the SNTP
>Clients? I know that the first solution is better and to be sure of the
>answer, it will depends on the network traffic, CPU, OS, etc but in theory
>this solution works for 1ms precision?

Not enough information. It depends entirely on the network, network delays,
etc. 



>Thank you everybody
>Barelo




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