Fujitsu PRIMEQUEST 2000 Series Tool Reference page 221

MMB Web-UI (Web User Interface) Operations
1.5 [Network Configuration] Menu
Time synchronization with NTP
This section describes the operational specifications for the NTP client.
- When starting time synchronization:
The NTP client on the MMB synchronizes the time at the start of operation, irrespective of the
time difference with the NTP server.
The NTP client on the MMB starts operation:
when the NTP services on the MMB are enabled (i.e., when [Enable] in the [NTP] field
-
is checked and the [Apply] button is clicked in the [Network Configuration] - [Date/Time]
window), or
when the MMB is reset, the MMB redundancy is switched, and the AC power is turned
-
from OFF to ON while the NTP services on the MMB are enabled.
- When starting time synchronization:
The time-adjusting method on the NTP varies depending on the NTP operation mode (Step mode
or Slew mode).
In Step mode, if the time difference between the synchronized NTP servers and the MMB is:
(1) within a range of -0.128 to +0.128 seconds, the NTP executes Slew adjustment, which
corrects the time at a rate of up to 0.0005 per second without reversal.
(2) outside a range of -0.128 to +0.128 seconds and within a range of -1000 to +1000
seconds, the NTP executes Step adjustment. (In this case, the clock may be reversed.)
(3) outside a range of -1000 to +1000 seconds, the NTP function stops.
In Slew mode, if the time difference between the synchronized NTP servers and the MMB is:
(1) within a range of -600 to +600 seconds (10 minutes) , the NTP executes Slew
adjustment, which corrects the time at a rate of up to 0.0005 per second without
reversal.
(2) outside a range of -600 to +600 seconds (10 minutes) and within a range of -1000 to
+1000 seconds (16 minutes and 40 seconds) , the NTP executes Step adjustment. (In
this case, the clock may be reversed.)
(3) outside a range of -1000 to +1000 seconds (16 minutes and 40 seconds) , the NTP
function stops.
- Time synchronization interval
The NTP client synchronizes at an interval of 64 to 1024 seconds. The initial synchronization
interval is 64 seconds. As the synchronization accuracy becomes stable, this interval gradually
doubles from 64 seconds to 128 seconds, then to 256 seconds, then to 512 seconds, and finally
to 1024 seconds.
This increment algorithm for the synchronization interval conforms to RFC 1305. For details, see
Sections 3.4.2 to 3.4.9 in RFC 1305.
Stratum of the NTP servers on the MMB
-
The stratum of the NTP servers on the MMB is the value of stratum + 1 of the synchronized
external NTP servers. Unless the NTP servers synchronize with external NTP servers, the
stratum is 5.
Support for leap seconds
-
The NTP on the MMB has no function for inserting leap seconds. Therefore, if you want to
associate the MMB time with leap seconds, you need to synchronize it with an external NTP
server that supports leap seconds.
If the NTP client on the MMB is set to Step mode, and the external NTP server slowly changes
the time for the leap second adjustment, the MMB time may be adjusted with the Step adjustment
when a time difference outside a range of -0.128 to +0.128 second occurs. To prevent the leap
second adjustment from using Step adjustment, use Slew mode.
220
CA92344-0539-04