{HEAD ~ A plurality} of retransmit servers in {TAIL ~ the network buffer portions} of the packets they respectively receive during the multicast session 
{ HEAD ~ A plurality } of retransmit servers in { TAIL ~ the network buffer portions } of the packets they respectively receive during the multicast session
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH