Automatic repeat request (ARQ) Break large files into packets FILE PKT PKT PKT Check received packets for errors Use a feedback channel to request retransmissions Retransmit packets containing errors acket Receive ACKAutomatic repeat request (ARQ) • Break large files into packets PKT H FI LE PKT H PKT H • Check received packets for errors • Use a feedback channel to request retransmissions • Retransmit packets containing errors packet ACK Sender Receiver