Myrinet and GM multi and broadcast

Does the Myrinet interface support a true multi or broadcast capability?
If so, is there a GM interface and benchmark that I can investigate this
with.  MPI Broadcast simply serializes the transfers to the receivers which
takes progressively longer.  This is a very important feature to broadcast
front end data transfers to all receiver nodes for sharing sensor data at
very high data rates.  Any information would be greatly appreciated.