I have two linux machines (A and B) on an isolated network. They must be time-synchronized. Machine A is powered intermittently and must serve the time, as it is connected to an authoritative time source (GPS). Machine B is only powered if machine A is powered, but it is an embedded linux device and its power state will change frequently. Neither machine has access to other systems. It's a closed network.
I understand that this is quite a tall order for NTP, as NTP usually expects to have contact with several servers. I'm having trouble getting this to work properly on Machine B. Machine A synchs to the GPS just fine, and machine B can reach machine A and even do time queries, but Machine A is not trusted (perhaps by itself?). After a solid hour of machine A being up, this suddenly changed and machine B worked. However, when machine A went down (and thus machine B), machine B is once again unable to find a good time synch.
Here's some ntpdate info. Please note that even when machine A's stratum is 1, the operation fails with the same output at the end.
10.10.10.1: Server dropped: strata too high server 10.10.10.1, port 123 stratum 16, precision -19, leap 11, trust 000 refid [10.10.10.1], delay 0.02614, dispersion 0.00000 transmitted 4, in filter 4 reference time: 00000000.00000000 Thu, Feb 7 2036 6:28:16.000 originate timestamp: d3a9bdc4.27ebb350 Thu, Jul 12 2012 21:19:00.155 transmit timestamp: bc17c803.b42dfffe Sat, Jan 1 2000 0:25:39.703 filter delay: 0.02625 0.02614 0.02618 0.02625 0.00000 0.00000 0.00000 0.00000 filter offset: 39544160 39544160 39544160 39544160 0.000000 0.000000 0.000000 0.000000 delay 0.02614, dispersion 0.00000 offset 395441600.451568 1 Jan 00:25:39 ntpdate: no server suitable for synchronization found
My guess is that machine A just doesn't trust itself for serving time. After 51 minutes (may have happened earlier, I don't know) of uptime and having its clock synch'd to GPS, machine A started to serve time correctly, and machine B picked it up. I need this to happen earlier. Like, within seconds if possible.
With the following configs (and a lot of waiting), it eventually succeeds.
Machine A ntp.conf:
server 127.127.28.0 prefer true minpoll 4 maxpoll 4 fudge 127.127.28.0 stratum 1 time1 0.420 refid GPS
Machine B ntp.conf:
server 10.10.10.1 prefer true minpoll 4 maxpoll 4
ntpq -c peers on Machine B without good time fix:
remote refid st t when poll reach delay offset jitter ============================================================================== 10.10.10.1 .STEP. 16 u 9 16 0 0.000 0.000 0.000
ntp1 -c peers on Machine B with good time fix:
remote refid st t when poll reach delay offset jitter ============================================================================== *10.10.10.1 SHM(0) 2 u 7 16 17 0.669 2.597 1.808
So, now the question becomes: how do I make Machine A trust itself quickly?
Some debug output from Machine A before and after machine B decides that Machine A is good enough to use..
~ # ntpq -c rv associd=0 status=c418 leap_alarm, sync_uhf_radio, 1 event, no_sys_peer, version="ntpd email@example.com Fri Feb 24 15:01:45 UTC 2012 (1)", processor="armv7l", system="Linux/126.96.36.199", leap=11, stratum=2, precision=-19, rootdelay=0.000, rootdisp=44.537, refid=SHM(0), reftime=d3ab0053.43b44780 Fri, Jul 13 2012 20:15:15.264, clock=d3ab0062.e7e03154 Fri, Jul 13 2012 20:15:30.905, peer=34819, tc=4, mintc=3, offset=0.000, frequency=0.000, sys_jitter=3.853, clk_jitter=36.492, clk_wander=0.000
~ # ntpq -c rv associd=0 status=0415 leap_none, sync_uhf_radio, 1 event, clock_sync, version="ntpd firstname.lastname@example.org Fri Feb 24 15:01:45 UTC 2012 (1)", processor="armv7l", system="Linux/188.8.131.52", leap=00, stratum=2, precision=-19, rootdelay=0.000, rootdisp=41.278, refid=SHM(0), reftime=d3ab0063.43b37856 Fri, Jul 13 2012 20:15:31.264, clock=d3ab006d.9ee53ec2 Fri, Jul 13 2012 20:15:41.620, peer=34819, tc=4, mintc=3, offset=0.000, frequency=43.896, sys_jitter=0.762, clk_jitter=36.953, clk_wander=0.000
ntp.conffiles and output from
ntpq -pwhen machine B is NOT getting good time from machine A? It could be marking machine A as a false ticker or something. When machine B isn't trusting machine A, is machine A synchronized with the GPS? (Output of
ntpstaton machine A.)