The value of tmnxOamTrProbeHistoryDataLen indicates the UDP data length
of the echo reply.
A valid value is returned when the test has a tmnxOamTrCtlTestMode
value of 'icmpTraceRoute', 'lspTraceRoute', 'p2mpLspTrace', or
'vccvTraceRoute'. Otherwise, this value is not significant and zero is
returned.