[ntp:questions] long linear network, time accuracy, and ntp strata

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Tue Oct 19 07:42:23 UTC 2010

Miernik, Jerzy (Jerzy) wrote:
> I have a question about how to use ntp in a long linear network. Assume there are 50 nodes with the one most in the West having GPS, and every node running ntpd:
>    node1 --- node2 --- node3 --- ... --- node50
>    GPS
> Which approach to synchronization would be better in terms of the time accuracy in nodes:
> 1. configure 'server node1 ...' in nodes 2, 3, ..., 50; or
> 2. use manycast for automatic client / server self-organization?
> Approach 1 seems to me to lead to inferior accuracy due to increasing distance between a client in nodex and server in node1, where routing in nodes node2, node3, ..., node(x-1) would add to jitter. Yet we would have one node stratum1 and all others stratum2, it would seem...
> I would think approach 2 with manycast would end up in smaller offsets (if any) between clocks, but would lead to clocks of stratum 16, 17, ..., 50, and I am not sure how ntpd would react in node16, node17, ..., node50.
> Could an expert please offer a comment on which approach would be preferable?

You would want to configure every single node2..node50 to talk directly 
to node1, using regular "server node1 iburst" config lines.


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

More information about the questions mailing list