PRISM MPI2-25 and MPX2-25 Media Analysis Platform User Manual
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Unicast system messages
Unicast messages require the address of the master be entered into the
Acceptable Master Table (AMT) in each slave. If there are multiple masters, the
IP address for each master must be entered in the AMTs of all the slaves.
In Unicast PTP systems, the slave must have the address of the master in its
acceptable master table because the slave initiates the communication with the
master. The slave sends several grant requests to the master requesting specific
rates for each message type. If the master accepts the grant requests, it will send
grant acknowledges. If the master denies the grant, the slave may send a new
grant request at a lower rate. This process may continue for several iterations
until the master and slave agree on a rate. The master and slave will then start
exchanging the PTP messages. If the master cannot support any of the rates
requested by the slave, then the slave will not be able to lock to the master.
Mixed mode
system
messages
In Mixed Mode systems, some messages are Multicast and some are Unicast. For
the SMPTE ST2059 profile, the Announce and Sync messages are sent as
Multicast. This allows devices to discover the active master. The Delay Request
messages are configured as Unicast, in some case with negotiation, and in other
cases without negotiation.
SMPTE profile
system
messages
For SMPTE profile systems, a given domain must use one type of message for all
Announce, Sync, and Follow-up messages. Therefore, all masters and slaves on
that domain must be configured for either Multicast or they all must be
configured for Unicast.
For SMPTE mixed mode, the Announce, Sync, and Follow up messages are
configured as Multicast, whereas the delay requests can be Multicast, Unicast, or
Unicast without negotiation. To use this combination with an SPG8000A master
clock generator, set the master and slave to any of the modes: Multicast, Mixed,
or Mixed without negotiation. The masters support all of the slave modes
simultaneously.
