Systems and methods for dynamically controlling bandwidth of connections are described. In some embodiments, a proxy for one or more connections may allocate, distribute, or generate indications of network congestion via one or more connections in order to induce the senders of the connections to reduce their rates of transmission. The proxy may allocate, distribute, or generate these indications in such a way as to provide quality of service to one or more connections, or to ensure that a number of connections transmit within an accepted bandwidth limit. In other embodiments, a sender of a transport layer connection may have a method for determining a response to congestion indications which accounts for a priority of the connection. In these embodiments, a sender may reduce or increase parameters related to transmission rate at different rates according to a priority of the connection.