The repair server 120A receives the response 505A and the FEC processor 185A therein reconstructs the two missing packets 283 and 284 from the combination of the FEC value 515, {TAIL ~ the data block} 500A, {HEAD ~ the FEC value} 515′ and the data block 500A′ 
The repair server 120A receives the response 505A and the FEC processor 185A therein reconstructs the two missing packets 283 and 284 from the combination of the FEC value 515 , { TAIL ~ the data block } 500A , { HEAD ~ the FEC value } 515′ and the data block 500A′
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH