{TAIL ~ The blocking time interval} is preferably greater than {HEAD ~ the round trip propagation time} for a message packet 
{ TAIL ~ The blocking time interval } is preferably greater than { HEAD ~ the round trip propagation time } for a message packet
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH