Client Rule 1 RTO Start -----> Time-out /restart Seq: Seq 17 Lost Seq: Seq Resent Lost Server Rule 1 (--- 1. The client sends a segment carrying bytes 1401 to 1700, which arrives at the sender site. 2. The server sends a segment carrying bytes 2001 to 2100 and acknowledging the first segment from the client, which arrives. 3. The client sends a segment carrying bytes 1701 to 1900 and acknowledging the segment received, but the segment is lost. 4. The client sends a segment carrying bytes 1901 to 2100, but the segment is lost. 5. Time out occurs at the client ACK-delaying timer site. The client resends a 500 ms Rule 2 Ack Time-out ACK-delaying timer Rule 2 500 ms Time-out segment in response to time-out, this packet arrived. 6. The server sends an acknowledgment after ACK- delaying timer expires. 7. Another time-out occurs at the client site. The client resends a segment in response to time-out, which arrives at the sender. 8. The server sends an acknowledgment after ACK- delaying timer expires. Time-out /restart Seq Resent Ack Stop C