ntp - How to synchronise clocks in a local network? -

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let assume have number of systems connected in local network , not connected internet. can best way ensure each of these clocks in sync? not necessary in sync utc time enough in sync amongst themselves.

i had thought of using ntp, setting ntp server in 1 of systems. need advise if more cumbersome compared requirement. advisable try manually compute round trip time , server time using tcp sockets?

solution small local network synchronized each other using undisciplined local clock of 1 of machines can done in simple ntp peer network 1 setup local clock backup if real time sources fail.

one example of multi-server/peer ntp network. notice how each ntp not have same servers listed. better use of peer sync. peer sync can match against different time results.

1a  1b     1c  1d     1e  1f      outside . \ / ...... \ / ...... \ / ..............    2a ---p--- 2b ---p--- 2c        inside   /|\        /|\        /|\  / | \      / | \      / | \ 3a 3b 3c   3e 3f 3g   3h 3i 3j  key: 1 = stratum-1, 2 = stratum-2, 3 = stratum-3, p = peer #diagram + more info: http://www.ntp.org/ntpfaq/ntp-s-config-adv.htm

ntp server a (myntp.server.a)

# undisciplined local clock. fake driver intended backup # , when no outside source of synchronized time available. server 127.127.1.0 fudge 127.127.1.0 stratum 10  server 0.pool.ntp.org iburst  server 1.pool.ntp.org iburst  peer myntp.server.b peer myntp.server.c

ntp server b (myntp.server.b)

server 2.pool.ntp.org iburst  server 3.pool.ntp.org iburst peer myntp.server.a peer myntp.server.c

if 1 server (e.g. myntp.server.a) ran local clock, sync - bad - @ least clocks on network stay - see more at: http://compgroups.net/comp.protocols.time.ntp/undisciplined-local-clocks/1874258#sthash.xngpzubj.dpuf

more information: http://doc.ntp.org/4.1.1/confopt.htm


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