I have a number of processes split into sender and receivers.
Senders read large quantities of randomly organised data into buffers for transmission to receivers.
When a buffer is full it needs to be transmitted to all receivers this repeats until all the data is transmitted.

Problem is that MPI_Bcast must know the root it is to receive from and therefore cant receive 'blind' from the first full sender.
Scatter would be inneffieienct because a few senders wont have anything to send - so its wasteful to transmit those empty buffers repeatedly. 

Any ideas?
Can Bcast recievers be promiscuous?

Thanks Randolph