Pure Stop and Wait Protocol Transmitter departure times at A Time packet CRC packet IIA packet 1 CRC ACK NAK arrival times at receiver Packet o Packet 1 ccepte Accepted Problem: Lost Packets Sender will wait forever for an acknowledgement Packet may be lost due to framing errors Solution: Use time-out ( TO) Sender retransmits the packet after a timeout Eytan modianoPure Stop and Wait Protocol Transmitter departure times at A Time ACK -----> NAK packet 0 CRC packet 1 CRC packet 1 CRC arrival times at receiver Packet 0 Accepted • Problem: Lost Packets – Sender will wait forever for an acknowledgement • Packet may be lost due to framing errors • Solution: Use time-out (TO) – Sender r etransmits the packet after a timeout Packet 1 Accepted Eyt an Modiano 3