[ntp:questions] Help appreciated
Richard B. Gilbert
rgilbert88 at comcast.net
Tue May 12 20:14:28 UTC 2009
Towli wrote:
> Hi all
>
> I found out that our Inet-Provider has stratum 1 servers available, and
> i intended to use these together with our newly acquired DCF77 machinery.
> I configured our DFC77 and the 2 external stratum 1 servers on our 2
> core switches to deliver Ntp to the rest of the network...
> Unfortunately (?) my switches seem to prefer these external time sources
> as opposed to our own internal DCF77 Furthermore i can se (from output
> below) that our internal DCF77 is listed as "invalid" ? ? ? Why is that?
> I have not yet set up our backup DCF77. When i do - should i loose the 2
> external sources and use solely internal NTPservers or what would your
> recommendations / best practice be, based on the output below ?
>
> Any advice is highly appreciated as i am on thin ice here, and it is an
> important task to implement NTP correctly on out network.
>
> Output: (for "anonymous" purposes in regards to my job i have marked the
> external ip's with xxx)
>
>
> /Towli - Denmark
>
>
> #sh ntp ass de
> 193.xxx.xxx.xxx configured, our_master, sane, valid, stratum 1
> ref ID .GPS., time CDB44C38.435EEBEB (21:27:52.263 CEST Tue May 12 2009)
> our mode client, peer mode server, our poll intvl 64, peer poll intvl 64
> root delay 0.00 msec, root disp 1.69, reach 377, sync dist 9.247
> delay 6.13 msec, offset 4.1194 msec, dispersion 4.30
> precision 2**18, version 3
> org time CDB44C68.7CC60B4F (21:28:40.487 CEST Tue May 12 2009)
> rcv time CDB44C68.7C8118AB (21:28:40.486 CEST Tue May 12 2009)
> xmt time CDB44C68.7AEB32B4 (21:28:40.480 CEST Tue May 12 2009)
> filtdelay = 6.13 6.12 5.57 8.21 5.10 6.33 5.98
> 5.05
> filtoffset = 4.12 6.02 8.18 9.58 13.80 16.39 19.32
> 22.59
> filterror = 0.02 0.99 1.97 2.94 3.92 4.90 6.64
> 8.59
>
> 193.zzz.zzz.zzz configured, selected, sane, valid, stratum 1
> ref ID .GPS., time CDB44C3C.894CBE10 (21:27:56.536 CEST Tue May 12 2009)
> our mode client, peer mode server, our poll intvl 64, peer poll intvl 64
> root delay 0.00 msec, root disp 1.80, reach 377, sync dist 7.889
> delay 5.43 msec, offset 4.2101 msec, dispersion 3.37
> precision 2**18, version 3
> org time CDB44C74.7DD78E42 (21:28:52.491 CEST Tue May 12 2009)
> rcv time CDB44C74.7D760EA9 (21:28:52.490 CEST Tue May 12 2009)
> xmt time CDB44C74.7C0F49F3 (21:28:52.484 CEST Tue May 12 2009)
> filtdelay = 5.43 6.73 5.94 5.89 6.13 4.82 5.07
> 5.49
> filtoffset = 4.21 5.25 7.64 10.08 12.67 16.30 17.74
> 20.33
> filterror = 0.02 0.99 1.97 2.94 3.92 4.90 5.87
> 7.83
>
> 10.200.138.20 configured, sane, invalid, stratum 1
> ref ID .DCF., time CDB44934.00000000 (21:15:00.000 CEST Tue May 12 2009)
> our mode client, peer mode server, our poll intvl 1024, peer poll intvl
> 1024
> root delay 0.00 msec, root disp 0.00, reach 377, sync dist 21.103
> delay 3.27 msec, offset -11.4426 msec, dispersion 7.02
> precision 2**6, version 3 <------------------------- what does this
> precission indicate ? Better or worse than 2**18 ?
Precision is normally expressed as a *negative* power of two! Assuming
that somebody dropped the minus signs somewhere, 2**-18 is better than
2**-8. Precision is the smallest possible difference between two
successive readings of the clock.
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