The document discusses TCP Reno, New Reno, and SACK and provides details on TCP Reno's congestion control algorithms. It explains that TCP Reno increases the congestion window by 1 for each new ACK when below the slow start threshold, and by 1/cwnd when above. It also describes TCP Reno's behaviors in response to timeouts, triple duplicate ACKs, and subsequent duplicate ACKs, which include retransmissions and adjusting the slow start threshold and congestion window.