The value of vRtrPimNgDataMtCGrpSrcDataMtThreshold indicates the
threshold in kilo-bits per second(kbps) for the group to which
this C-(S,G) belongs.
For a C-group G configured with a threshold, a C-(S,G) is
mapped to a Data Multicast Tunnel (MT) only if the C-(S,G)'s rate
exceeds this configured threshold.