The repair server detects that packets are missing from the session it receives and in response, it sequentially requests {TAIL ~ the missing packets} from {HEAD ~ respective ones} of the plurality of retransmit servers 
The repair server detects that packets are missing from the session it receives and in response , it sequentially requests { TAIL ~ the missing packets } from { HEAD ~ respective ones } of the plurality of retransmit servers
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH