The value of tmnxPtpPeerRxTimeStampPoint indicates the reference point
used to generate the PTP timestamp for the last received PTP event
packet. If no event packets have been received, the value is
'unknown(0)'. If PTP event packets are received on an interface
with tmnxPtpVRtrIfAdminState set to 'inService(2)', and the destination
IP address of the received packet is either the local IPv4 address
of the interface or the PTP system IPv4 address, the value is
'port(1)'. Otherwise, the value is 'cpm(2)'.