The value of tmnxOamLspTrCtlDownstreamMapTlv specifies the type of
downstream mapping TLV to insert in the MPLS echo request PDU when
launching the test.
When an LSP trace route test is created, the value of this object
defaults to the value of the global configuration object
tmnxOamMplsEchoDownstreamMapTlv.
The supported object combinations for LSP trace route tests are listed
in the tmnxOamLspTrCtlTable DESCRIPTION clause.