The value of tmnxPtpPeerTxTimeStampPoint indicates the reference point
used to generate the PTP timestamp for the last transmitted PTP event
packet. If no event packets have been transmitted, the value is
'unknown(0)'. If PTP event packets are transmitted out an interface
with tmnxPtpVRtrIfAdminState set to 'inService(2)', the value is
'port(1)'. If PTP event packets are transmitted out an interface with
tmnxPtpVRtrIfAdminState set to 'outOfService(3)', the value is
'cpm(2)'.