The Time Synchronization Hierarchy |
The NTP daemon can not only adjust its own computer’s system time. Additionally, each daemon can be a client, server, or peer for other NTP daemons:
These features can be used to set up a hierarchical time synchronization structure. The hierarchical levels of the time synchronization structure are called stratum levels. A smaller stratum number means a higher level in the hierarchy structure. On top of the hierarchy there is the daemon which has the most accurate time and therefore the smallest stratumnumber. By default, a daemon’s stratum level is always one level below the level of its reference time source. The top level daemon often uses a radio clock as reference time source. By default, radio clocks have a stratum number of 0, so a daemon who uses that radio clock as reference time will be a stratum 1 time server, which has the highest priority level in the NTP hierarchy. In large networks it is a good practice to install one ore more stratum 1 time servers which make a reference time available to several server computers in each department. Thus the servers in the departments become stratum 2 time servers which can be used as reference time source for workstations and other network devices of the department. Unlike in telecom applications where the word stratum is used e.g. to classify oscillators according to their absolute accuracy, the term stratum in the NTP context does not indicate a certain class of accuracy, it’s just an indicator of the hierarchy level. |
http://www.meinberg.de/english/info/ntp.htm
1.Sync the time with ntp, login as root, type
#ntpdate ntp_ip_address
2.Edit file /etc/ntp.conf and add
server ntp_ip_address
driftfile /etc/ntp.drift
tracefile /etc/ntp.trace
I.E.
more /etc/ntp.conf
server time_server01 prefer
server time_server02
broadcastclient
driftfile /etc/ntp.drift
tracefile /etc/ntp.trace
3.smitty xntpd
select BOTH
- Let the daemon run for about 10 mins then type:
lssrc –ls xntpd
Program name: /usr/sbin/xntpd
Version: 3
Leap indicator: 00 (No leap second today.)
Sys peer: time_server01
Sys stratum: 2
Sys precision: -18
Debug/Tracing: DISABLED
Root distance: 0.000458
Root dispersion: 10.166382
Reference ID: 10.1.1.10
Reference time: d3b125c4.78c4d000 Wed, Jul 18 2012 15:08:36.471
Broadcast delay: 0.003906 (sec)
Auth delay: 0.000122 (sec)
System flags: bclient pll monitor filegen
System uptime: 1102 (sec)
Clock stability: 1358.841064 (sec)
Clock frequency: -16.000000 (sec)
Peer: time_server02
flags: (configured)(sys peer)
stratum: 2, version: 3
our mode: client, his mode: server
Peer: time_server01
flags: (configured)(sys peer)(preferred)
stratum: 1, version: 3
our mode: client, his mode: server
Subsystem Group PID Status
xntpd tcpip 12283954 active