[ntp:questions] Is a high-stratum falseticker possible? Complex configuration and unexpected result

rumegauu at ugpa.ru rumegauu at ugpa.ru
Thu Apr 26 10:39:59 UTC 2012


Hello,
I designed a complex configuration for a huge intranet network some
time ago. The network  is completely isolated from the Internet and
uses internal time sources. Circuits aren't any good there, so I
decided to use some peer-to-peer synchronization in addition to the
main hierarchy and enabled tos orphan.

I hardly need to say that most of the hosts are embedded devices which
aren’t easily accessible. I've built ntp4.2.6 from the tarball and
deployed it across the devices. Various simulations were passed with
success before the launch in 2011. It has been running well for 6
months until some unexpected troubles come.

Could you explain to me HOW this is possible? The prime server with
stratum 6 declared falseticker, when the peer with stratum 12 is
considered to be true.


NTPQ output:
C:\Users\public> ntpq -n 25.18.0.124
ntpq> raw
Output set to raw

ntpq> pe
     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
x25.18.0.235     LOCAL(0)         6 u  272  128  377   17.354
90575.7   4.384
x25.18.0.103     25.18.0.235      7 u  302  128  377   37.938
34576.2  95.391
x25.18.0.105     25.18.0.116     12 u  805 1024  376   52.333
3418.78  29.265
 25.18.0.106     25.18.0.124     12 u  277 1024  377   39.883
14.698  24.281
x25.18.0.107     25.18.0.113     11 u  713 1024  376  184.678  1175.09
778.300
*25.18.0.108     25.18.0.112     12 u  457 1024  367   77.007
-6.868  81.954
-25.18.0.109     25.18.0.115     13 u  222 1024  377  103.053
-318.49  54.671
 25.18.0.112     25.18.0.109     11 u  615 1024  355   83.708
-101.42  49.904
 25.18.0.113     127.0.0.1       10 u 1220 1024  376  112.932
-145.68  32.612
x25.18.0.114     25.18.0.118     13 u 1050 1024  376    6.649  -35174.
487.947
+25.18.0.115     25.18.0.112     13 u  589 1024  356   68.001
5.703  30.844
 25.18.0.116     25.18.0.124     13 u  210 1024  377   50.452
-42.981  29.490
-25.18.0.118     25.18.0.116     12 u  387 1024  377   38.929
-103.65  42.252
+25.18.0.122     25.18.0.115     13 u  697 1024  376   26.176
-10.287  33.839
x25.18.0.123     25.18.0.115     13 u  886 1024  376   10.380
5543.16  75.828
 25.18.0.124     .INIT.          16 u    - 1024    0    0.000
0.000   0.000

ntpq> rv
associd=0 status=0x0618,
version="ntpd 4.2.6p1 at 1.2158 Tue Sep 21 11:13:30 UTC 2010 (1)",
processor="x86pc", system="QNX/6.3.2", leap=0, stratum=11,
precision=-10, rootdelay=103.053, rootdisp=421.974, refid=25.18.0.109,
reftime=0xd339131d.ef9d3607, clock=0xd339175b.844810af, peer=52456,
tc=10, mintc=3, offset=-318.499, frequency=-13.848, sys_jitter=82.308,
clk_jitter=99.267, clk_wander=0.029


ntpq> as
 ind assid status  conf reach auth condition  last_event cnt
===========================================================
  1 52450  9124   yes   yes  none falsetick   reachable  2
  2 52451  9124   yes   yes  none falsetick   reachable  2
  3 52452  9124   yes   yes  none falsetick   reachable  2
  4 52453  901a   yes   yes  none    reject    sys_peer  1
  5 52454  9124   yes   yes  none falsetick   reachable  2
  6 52455  961a   yes   yes  none  sys.peer    sys_peer  1
  7 52456  933a   yes   yes  none   outlyer    sys_peer  3
  8 52457  901a   yes   yes  none    reject    sys_peer  1
  9 52458  901a   yes   yes  none    reject    sys_peer  1
 10 52459  9124   yes   yes  none falsetick   reachable  2
 11 52460  941a   yes   yes  none candidate    sys_peer  1
 12 52461  901a   yes   yes  none    reject    sys_peer  1
 13 52462  931a   yes   yes  none   outlyer    sys_peer  1
 14 52463  941a   yes   yes  none candidate    sys_peer  1
 15 52464  9124   yes   yes  none falsetick   reachable  2
 16 52465  8011   yes    no  none    reject    mobilize  1

ntpq> rv 52456
associd=52456 status=0x933a,
srcadr=25.18.0.109, srcport=123, dstadr=25.18.0.124, dstport=123,
leap=0, stratum=13, precision=-10, rootdelay=126.938,
rootdisp=682.297,
refid=25.18.0.115, reftime=0xd339128e.863bdce7,
rec=0xd339173c.e54e2599,
reach=0xff, unreach=0, hmode=1, pmode=1, hpoll=10, ppoll=10,
headway=583, flash=0x0, keyid=0, offset=-318.499, delay=103.053,
dispersion=28.132, jitter=54.671, xleave=1.476,
filtdelay= 114.41 103.05 260.30 219.31 151.17 117.18 129.10 203.67,
filtoffset= -288.54 -318.50 -397.15 -386.71 -356.67 -339.87 -359.52
-393.27,
filtdisp= 1.95 17.78 33.64 49.52 65.18 81.41 96.89 112.42

The config file on 25.18.0.124 is similar that:

server 25.18.0.235 iburst minpoll 4 maxpoll 7
server 25.18.0.103 iburst minpoll 4 maxpoll 7
peer 25.18.0.105 minpoll 10
peer 25.18.0.106 minpoll 10
peer 25.18.0.107 minpoll 10
peer 25.18.0.108 minpoll 10
peer 25.18.0.109 minpoll 10
peer 25.18.0.112 minpoll 10
peer 25.18.0.113 minpoll 10
peer 25.18.0.114 minpoll 10
peer 25.18.0.115 minpoll 10
peer 25.18.0.116 minpoll 10
peer 25.18.0.118 minpoll 10
peer 25.18.0.122 minpoll 10
peer 25.18.0.123 minpoll 10
peer 25.18.0.124 minpoll 10
tos orphan 12
tos maxdist 5
tinker panic 0
disable auth
driftfile /var/ntp.drift

Thank you for any help you can provide.



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