Another way this can be accomplished is by transmitting {HEAD ~ the missing packets} in a unicast session from the retransmit servers to {TAIL ~ the repair server} 
to
Another way this can be accomplished is by transmitting { HEAD ~ the missing packets } in a unicast session from the retransmit servers to { TAIL ~ the repair server }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL