[ntp:questions] Compensating for asymmetric delay on a per-peer/server basis?

Paul tik-tok at bodosom.net
Fri Sep 12 13:06:42 UTC 2014


On Thu, Sep 11, 2014 at 3:50 PM, mike cook <michael.cook at sfr.fr> wrote:
>   Yup, AsymmetricDSL does have different up/down bit rates. What I really meant was that the difference would not explain his issue.
>   ex: with a 12Mbps down rate and 1.3Mbps up rate, the ratio is around 40usec to 300usec transfer of a 48byte NTP packet.

I was thinking closer to 1ms assuming a 10:1 asymmetry.  In any case
it would helpful to know the link speeds, delay and the sign of the
offset i.e. ntpq output from each end might be illuminating.  I also
see consistent 2ms offsets between my stratum 1 servers and external
stratum 1 servers.  Looking on the latter two I see the same offset
with opposite sign.  I have a 30/5 link.

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
o127.127.22.0    .GPPS.           0 l    1    8  377    0.000   -0.007   0.008
 2610:20:6f15:15 .ACTS.           1 u  111  128  377   35.726    2.098   0.153
 2620:cc:8000:80 .GPPS.           1 u   47   64  377   35.532    2.034   0.304
 2620:cc:8000:40 .GPPS.           1 u    2   64  377   35.308    2.054   0.675


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