Explicit Retransmission

2. Explicit Retransmission

- P transmits I-frame and starts timer

- S ACKs on receipt of error free I-frame

- S NAKs on receipt of corrupt I-frame

- P can transmit another I-frame on receipt of error free ACK

- P retransmits I-frame on timeout or NAK

- corrupt Frames are discarded (I-Frames, ACKs, and NAKs)