Tcp Congestion Avoidance Using Explicit Buffer Notification

This paper proposes to modify the TCP congestion control mechanism by allowing network routers to supply Explicit Buffer Notification (EBN) to the TCP data sender. The TCP sender runs an algorithm that uses the EBN feedback to compute the control window. The EBN plays the role of a generalized Advertised Window so that the EBN TCP results to be a natural extension of the current TCP flow control. The key feature of the proposed congestion avoidance algorithm is that it is not based on packet loss to detect congestion. As a consequence, it results to be suitable for applications that are sensitive to the delay or loss of individual packets, such as interactive traffic, and for data transfer over wireless links where packet loss will occur more often due to unreliable links than due to congestion. The proposed control works over connection paths with any bandwidth×delay product. Its strength lies in the fact that it is designed via classical control theory and, therefore, its dynamic properties, such as no cell loss and full link utilization, can be rigorously and easily shown via mathematical analysis. Finally, Fair Queuing at the routers decouples the flows and ensures fairness.