098-00720-000 Revision D1 – February, 2018 SyncServer 600 Series User’s Guide 99
Chapter 4
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Ref Id This is a four-byte field used to identify the reference clock source. At
initialization, while the stratum is 16, this field shows the progression of the NTP
clock PLL. The field will start with a value of INIT (may be displayed as
73.78.73.84, the ASCII decimal values).
Once a peer has been selected, the clock may be stepped, in which case the
reference ID field will change to STEP (or 83.84.69.80). Once the PLL is locked,
the stratum will be updated and the reference ID will identify the selected peer. In
the case of a SyncServer operating at stratum 1, the reference ID will display the
source for the local timing reference (e.g., GNSS, IRIG, FREE). In the case where
the selected peer is another NTP server, the reference ID will display the IP
address of the server or a hash unique to the association between the
SyncServer and the remote server.
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 GNSS. 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.
Table 4-6. NTPd Associations Parameters (Continued)
Parameter Description
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