Spectracom Corporation
Model 9289
NetClock/NTP Network Time Provider Instruction Manual
3-23
The grids on the NTP References screen allow the user to define, by IP address or hostname,
the locations of other NTP servers to use as time references (instead of the configured
NetClock’s GPS reference) and the locations of other NTP servers to use as peers. Peers are
NTP servers at the same stratum level that are used as an additional check on the NetClock’s
timing accuracy. This prevents it from moving to stratum levels farther away from Stratum 1 if
the primary timing reference is lost. The maximum number of Peers allowed is 12. It is
recommended to use one or more Peers when you desire to provide mutual backup. Each peer
is normally configured to operate from one or more time sources including reference clocks or
other higher stratum servers. If a peer looses all reference clocks or fails the other peers
continue to provide time to other clocks on the network.
NTP servers can be configured as potential time references. The maximum number of NTP
servers used as time references allowed is 12. For best results, more than 4 NTP time servers
are recommended. As few as 1 NTP time server may be used, however, depending on your
needs and network timing architecture. A specific NTP server can be configured as the
preferred time reference by selecting the preferred checkbox. Only a single time reference can
be selected as preferred and only when the Netclock is not in Stratum-1 mode using a Stratum-
0 reference such as GPS, IRIG, Modem, or Serial Time Code Input.
For both NTP Peers and NTP Servers the Minimum and Maximum Poll rate for NTP packets
can be configured. Both NTP Peers and NTP Servers support either manually configured
Symmetric Key-ID/Key string pairs or the use of Auto-Key. However, these choices are mutually
exclusive and must be identically configured on both the Netclock and the NTP Peer or NTP
Server. If the Symmetric Key-ID/Key string pair method is selected the Key-ID must be first
defined on the Symmetric Key page.
The entry for NTP Peer or NTP Server can be deleted by checking the Clear button and
entering submit.
Figure 3-28: NTP References Screen (1 of 2)
Summary of Contents for 9289
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