Abstract:

As the algorithm of explicit congestion notification （ECN） in RFC 3168 recommends the gateway to drop packets when the average queue length in the gateway buffer exceeds the upper queue threshold, the network throughput may be too low. In order to improve the system performance, this paper proposes an algorithm named Long-Queue Random Drop （LQRD）. In the proposed algorithm, the gateway drops packets according to a drop probability function when the average queue length in the gateway buffer exceeds the upper queue threshold, thus limiting the continuous increase in queue length. The drop probability function synthetically considers the average queue length, the buffer size, the link capacity and the average queue delay. Simulated results show that the proposed algorithm ensures high throughput, short delay and robust connectivity for long queue length in the gateway buffer. The analytical model of the proposed algorithm is finally analyzed by using the nonlinearly differential equation.

Key words: gateway, congestion control, explicit congestion notification, random early detection