A greedy source is a traffic generator in a communication network that generates data at the maximum rate possible and at the earliest opportunity possible.^[1] Each source always has data to transmit, and is never in idle state due to congestion avoidance or other local host traffic shaping. One new data-packet is generated when the transmission of previous packet is completed, meaning that the sender side queue is never congested. A greedy session is a time-limited packet flow or data stream at maximum possible rate.

A greedy source traffic generation simulation model, or a greedy traffic generator, is useful when simulating and analysing or measuring the maximum throughput of a network.