There is a plurality of {HEAD ~ retransmit servers} in {TAIL ~ the network buffering portions} of the packets they respectively receive during the session 
There is a plurality of { HEAD ~ retransmit servers } in { TAIL ~ the network buffering portions } of the packets they respectively receive during the session
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH