On 2010-10-18, Miernik, Jerzy (Jerzy) <[email protected]> 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
What does "long linear network" mean? Does it really mean that all network traffic between node 1 and node 50 must pass through eachof the other machines ( eg because all have two network cards and the only connection from node i to i-1 is via one card and from i to i+1 is via the other network card on machine i?) If so, you will have a horribly slow network no matter what you do. Almost always direct connection is more accurate-- the outbound and inbound network times are measured for each packet. Not assumed. But as said by others, you want each of those nodes requesting time directly from node 1. ( also note that a chain of 50 machines each asking time from the previous one exhauses the possible stratum numbers and it will not work. ) > > 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? > Sincerely, > Jerzy. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
