The value of tmnxOamPingHistoryDataLen indicates for an 'lspPing'
the UDP data length of the echo reply, and for 'icmpPing' normally
the length starting after the IP header of the echo reply. For
'ethCfmLoopback' and 'ethCfmTwoWaySlm' the value is the number of
octets in the Value field of the Data TLV of the Ethernet CFM loopback
packet (zero if the packet has no Data TLV).
For other types of probes, this value is not significant and is
set to 0.