A method and apparatus for congestion control of a Transmission Control Protocol (TCP) connection. A TCP source monitors received acknowledgments (ACKs) and uses header information associated with the ACKs to determine an amount of data delivered at a TCP receiver. The amount of delivered data, divided by the time requited to deliver the data, gives a measure of instant data rate. The instant data rate is input to a filtering and averaging process to generate an estimate of the end-to-end bandwidth share or data rate of the connection. For the entire duration of the connection, the TCP source updates its estimate of the end-to-end bandwidth share every time an ACK is received. The estimate of the end-to-end bandwidth share is used the reset a congestion window and a slow start threshold whenever packet loss is indicated such as whenever a timeout expires or whenever three (3) duplicate ACKs are received.