Symmetricom TimeProvider 500, Руководство пользователя

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62 TimeProvider 500 2.0 User’s Guide 098-00172-000 Revision A – December, 2009
Chapter 3 Operations
Time-Setting
Time-Setting
In TimeProvider 500 version 1.0, time could only be set by the user with the “set
clock” CLI command. In Version 2.0, the local clock-setting method continues to be
supported with the
set clock time CLI command, but time-setting from a
grandmaster as a PTP-time related reference is added in version 2.0.
When the TimeProvider 500 receives its time from a grandmaster clock, the time is
continuously monitored and updated. Sudden jumps compared to the TimeProvider
500’s current time setting are recorded in the event log and various show
commands.
Other time-related CLI commands have been introduced in Version 2.0 so that the
user can select a timescale and make timezone adjustments when reporting time.
See
set clock timescale and set clock timezone for more information.
IPDV
The TimeProvider 500 can make IPDV (IP Packet Delay Variation) measurement.
These will be made on the packet flows to the currently-used grandmaster. Sync
packets will be used for forward measurements and delay packets used for the
reverse measurements. The following measurements can be made:

Forward and Reverse IPDV% below Threshold : These results use the
set
ipdv <threshold>
setting to define the boundary and
set ipdv interval
<value>
to define the data collection window. The results reported (one for each
flow direction) are the percentage of delay variation measurements made within
the data collection window that were smaller than the defined threshold.

Forward and Reverse Maximum IPDV : These results use
set ipdv interval
<value>
to define the data collection window. The results reported (one for each
flow direction) are the maximum delay variation measurement made within the
data collection window. Results are in usec.

Forward and Reverse Inter-Packet Jitter : These results use the
set ipdv
pacing <samples>
setting to define the spacing of the inter-packets and
set
ipdv interval <value>
to define the data collection window. The results
reported (one for each flow direction) are an estimate of the packet-to-packet
jitter observed within the defined data collection window. Results are in usec.
Note : If a grandmaster is the reference for time, any local setting via
the
set clock time
CLI command will be overridden by the
grandmaster clock reference.