Definition:
Transmission Control Protocol is the connection-oriented protocol that verifies IP packets are sent and received reliably. TCP relies on a sliding-window (slide the window to the receiver with data and then wait for the receiver to slide the window back ACKnowledging receipt of data) approach for congestion control. TCP connections provide end-to-end flow control to limit the number of packets in the network. The flow control is enforced by two windows - Sender-CWMD-Congestion WiNDow and receiver RCVWND-ReCeiVer WiNDow enforced by the Receiver as measure of its buffering capacity. The CWND is maintained by the Sender as means and measure of the capacity of the network. The Sender sends data packets one window at a time, and cannot send more than the minimum of RCVWND and CWND into the network.