[ntp:questions] Asymmetric lines
John Pettitt
jpp at cloudview.com
Fri Feb 4 20:06:25 UTC 2005
Hi all
I just put up a stratum 1 server (FreeBSD using the GPS18 with PPS)
on the end of a very asymmetric line (6000 kbps down 608 kbps up).
When I look on the local machine (gatekeeper.no-such-agency.net) I see this:
ntpq> pe
remote refid st t when poll reach delay offset
jitter
==============================================================================
*GPS_NMEA(0) .GPS. 0 l 8 16 377 0.000 0.003
0.002
LOCAL(0) 73.78.73.84 5 l 1 64 377 0.000 0.000
0.002
+[stratum1-a] .GPS. 1 u 29 64 377 21.147 2.068
9.112
+[stratum2-b] .CDMA. 1 u 51 64 377 17.442 2.019
6.896
+time.sr.sonic.n 63.192.96.10 2 u 37 64 377 10.896 0.891
0.579
note: names of the stratum 1 servers edited
However when I look from one of my other boxes
(eschelon.no-such-agency.net in a server farm connected by multiple
OC12's) I see
ntpq> pe
remote refid st t when poll reach delay offset
jitter
==============================================================================
LOCAL(0) 73.78.73.84 5 l 57 64 377 0.000 0.000
0.002
*gatekeeper.no-s .GPS. 1 u 777 1024 377 21.392 -1.933
0.098 <- my S1 server
+[stratum1-a] .GPS. 1 u 791 1024 377 7.456 -1.524
0.421
+[stratum1-b] .CDMA. 1 u 789 1024 377 3.446 -1.171
0.216
Again the names of the stratum 1's edited but they are the same servers
as above.
So I'm seeing a 2ms offset on the box itself and about 600ms from the
outside world. I probably wouldn't care about this except that the
offset seems to be stopping ntpd on my S1 from backing off it's poll
intervals (it's been stuck at 64 for 12 hours).
I seem to recall an asymmetric fudge patch being discussed but I can't
find it. Does anybody have a copy? (or other suggestions for tweaking
the setup)
John
P.S. both gatekeeper and eschelon are part of pool.ntp.org
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