Telestream PRISM MPI, Руководство пользователя

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Application Information
IP Session Application
PRISM MPI-MPX User Manual
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Delay Message Interval: For Multicast communication mode, the only delay
message interval allowed is "Follow Master". In this mode, the slave sets the delay
request rate according to the information sent by the master in the delay response
message.
Note:
The PRISM monitor currently supports Multicast communication mode and
SMPTE mixed mode without negotiation. In later firmware releases, other
communication modes will be supported.
•
Grandmaster BCMA Values: Lists these values for the Grandmaster BCMA (Best
Master Clock Algorithm) in order of precedence:
– Priority 1: This parameter defines which clocks are allowed to be considered as
masters. To be considered as a master, the value should be set to 128 or less.
Priority 1 is the first criteria in the BMCA, so if Priority 1 is set to a lower value than
other devices on the system, then it is chosen even if the clock quality is poor.
Typically, all the masters in a domain should have the same value for the Priority
1 parameter.
– Clock Class: This value characterizes the TAI (International Atomic Time)
traceability. The clock class value varies to indicate the type of reference in use by
the Grandmaster clock. For example, when locked to GPS the PTP grandmaster
reports a class 6. However, if in holdover mode after locking to GPS, then it
reports a class of 7.
– Clock Accuracy: This value characterizes the clock accuracy for the purpose of
determining the best master clock.
– Clock Variance: This value is reported by the PTP master to indicate the variance
of the clock over a one second interval. A lower number indicates a more stable
clock and is preferred by the BMCA.
– Priority 2: This parameter is used to break the tie between masters that have the
same clock quality. Several values may be used to define a hierarchy of devices.
Most profiles use 128 as a default, so a value of 127 or lower would indicate a
preferred master.
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Clock Source: The clock source field is not used by the BMCA. The field is set to
indicate the type of reference in use by the Grandmaster clock.
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Communication Mode: There are three basic message modes for PTP: Multicast,
Unicast, and mixed Multicast and Unicast. For full Multicast or Unicast modes, all of
the PTP messages are sent in the selected mode type.
Note: The PRISM monitor currently supports Multicast communication mode and
SMPTE mixed mode without negotiation. In later firmware releases, other
communication modes will be supported.
For some profiles, such as some telecom profiles and the SMPTE ST2059 profile, a
mixture of Multicast and Unicast are allowed. On the SMPTE profile unique mixed