098-00720-000 Revision B – April, 2016
SyncServer 600 Series User’s Guide
81
Chapter 4
Navigation Windows
Stratum
The stratum level of the remote clock in the NTP hierarchy. Lower values are
given more emphasis. For the local Hardware Clock, stratum 0 is a special value
that indicates the Hardware Clock it is synchronized by a "timing root" reference
such as GPS1. Values in the range of 1 through 15 indicate the number of steps
the remote NTP connection is from its timing root. Stratum 16 is a special value
that indicates that the remote connection is not synchronized. The stratum
reported by the SyncServer is incremented by one from its synchronizing peer.
For example, while synchronized to the Hardware Clock (Stratum 0), the stratum
of the SyncServer is one (Stratum 1).
Reach
This is an 8-bit shift register that keeps track of the last 8 attempts to reach the
remote end of the association. New bits are added to the rightmost end of the
register (1 for reached or 0 for unreached) and old bits "fall off" the left hand side.
The shift register is represented in octal. For example, by converting "377" from
octal to binary, one gets "11111111", indicating 8 successful polls. For a sequence
of eight successful polling attempts on a new association, the octal value of
Reach increases as follows: 1, 3, 7, 17, 37, 77, 177, 377. If the value isn't one of
those just shown, there may be a problem polling the remote end of the
association. If the value remains at 0, or decreases to 0, the association is
becoming unreachable. The reach value stays 0 if the SyncServer is a broadcast
or multicast server.
Offset (ms)
The time offset between the SyncServer and the remote server, in seconds, of
the last poll. The NTP daemon's clock selection algorithm gives preference to
lower Offset values.
The Offset for the Hardware Clock is usually in the microsecond range. For
external NTP associations, the offset is affected by the time base of the remote
node and the characteristics of the network path, with values typically in the 1 -
10 millisecond range.
Delay (ms)
The total delay, in seconds, of the round trip to the remote end of the NTP
association. For example, a value of "0.07817" equals approximately 78
milliseconds. The Delay for the Hardware Clock is "0". For most NTP
associations, typical values range from tens to hundreds of milliseconds. The
NTP daemon's clock selection algorithm gives preference to lower Delay values.
Disp (ms)
Dispersion represents the maximum error of the SyncServer relative to the NTP
association.There are two components in dispersion, those determined by the
peer relative to the primary reference source of standard time and those
measured by the SyncServer relative to the peer. They provide not only precision
measurements of offset and delay, but also definitive maximum error bounds, so
that the SyncServer can determine not only the time, but the quality of the time as
well.
Poll (s)
The length of the interval (in seconds) with which the SyncServer polls the
remote server, usually starting at 64 seconds and gradually increasing to 1024
seconds. Valid values range from 16 to 65535, increasing by powers of 2. The
polling interval for the Hardware Clock is fixed at 16 seconds. The
user-configured Minimum and Maximum Poll Interval settings on the NTP -
Config page limit this interval.
Table 4-5. NTPd Associations Parameters
Parameter
Description
