Hello ntp.org guys, I am trying to reproduce synchronization lost and time reset (big step) to prove my understanding about time jump on NTP Server and its consequence.
Here is how I am trying to reproduce. Environment: NTP Server: Linux Redhat 2.6.32-358.18.1.el6.ppc64 (RHEL 6.4 on POWER) stratum 2, server time1.nimt.or.th prefer server time2.nimt.or.th server time3.nimt.or.th NTP Client: AIX 7.1 TL3 SP2 /etc/ntp.conf server 172.20.111.145 driftfile /etc/ntp.drift tracefile /etc/ntp.trace 1. start xntpd on AIX to synchronized time with NTP Server /usr/sbin/xntpd -D 5 -l /tmp/testcase/xntpd_debug.log 2. after reachability value returned from ntpq -p on ntp client is 377, go to NTP Server and increase time for 30 seconds ahead. [root@powerlinux02 ~]# date Tue Jul 22 07:43:59 ICT 2014 [root@powerlinux02 ~]# date +%T -s 07:44:30 07:44:30 3. back to AIX NTP client, expected to see time reset and synchronization lost in /tmp/testcase/xntpd_debug.log Result: I see only synchronisation lost but no time reset. even though the offset is around 15 s. at 07:51:09 22 Jul 07:51:09 ntpdate[16449672]: step time server 172.20.111.145 offset 15.339173 22 Jul 07:39:36 xntpd[5636240]: synchronized to 172.20.111.145, stratum=2 22 Jul 07:44:56 xntpd[5636240]: synchronisation lost 22 Jul 07:50:15 xntpd[5636240]: synchronized to 172.20.111.145, stratum=2 22 Jul 07:54:00 xntpd[5636240]: synchronisation lost ================================================================== I am suspecting that the following time step happened on ntp client after NTP server get synchronized to its time source (stratum 1) ============== NTP Client ====================================== 22 Jul 08:10:45 xntpd[5636240]: synchronized to 172.20.111.145, stratum=2 22 Jul 08:10:45 xntpd[5636240]: step: -11.406840016 sec, sys_clock_offset = 11.406422555 sec, adjtv = 11.406423 sec, timetv = 1405991445.401204 sec 22 Jul 08:10:33 xntpd[5636240]: step: new timetv = 1405991433.994781 sec 22 Jul 08:10:33 xntpd[5636240]: time reset (step) -11.406840 s 22 Jul 08:10:33 xntpd[5636240]: synchronisation lost 22 Jul 08:15:53 xntpd[5636240]: synchronized to 172.20.111.145, stratum=2 =============================================================== ============== NTP Server ====================================== Jul 22 07:42:45 powerlinux02 ntpd[31714]: synchronized to 203.185.69.60, stratum 1 Jul 22 07:51:17 powerlinux02 ntpd[31714]: time reset -11.404767 s Jul 22 07:54:56 powerlinux02 ntpd[31714]: synchronized to 203.185.69.59, stratum 1 Jul 22 07:55:16 powerlinux02 ntpd[31714]: synchronized to 203.185.69.60, stratum 1 Jul 22 07:58:11 powerlinux02 ntpd[31714]: time reset -15.341662 s Jul 22 08:06:15 powerlinux02 ntpd[31714]: synchronized to 203.185.69.60, stratum 1 ============================================================= My ultimate goal is to figure out that time jump is technically possible on NTP server when it is synced to its time source. from the data above. It seems that NTP client believe NTP Server when NTP Server is synced to its time source. What I see from the real problem is that NTP Client break sync with NTP Server A and reset time for X s ahead. NTP Client then get syncd with NTP Server B and reset time for X s backwards. I just want to know - who changed its time. stratum1 time source or NTP Server? - which cause NTP client to reset time immediately (no sync lost without reset like in this case). Please help advise. Thank you very much. Thanachit W. _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
