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