Early Packet Discard option used for this VCL.
The use is as follows:
enable(1)
Packet-discard is enabled.
disable(2)
Packet-discard is disabled.
useTrafficDescr(3)
Packet-discard in the receive direction is as specified by
the atmTrafficFrameDiscard value in row corresponding to
atmVclReceiveTrafficDescrIndex. For VCLs of type
spvcInitiator, the packet-discard in the reverse direction
is as specified by the atmTrafficFrameDiscard value in row
corresponding to atmVclTransmitTrafficDescrIndex.