What If the End Systems Knew the Bandwidth Available in the Network?

In this paper we propose Open Box Transport Protocol (OBP), a mechanism that provides information to the end systems about the current state of the network path. With this information (essentially the available bandwidth and the most restricted link capacity) the end systems can efficiently use the network resources. OBP is easy to implement because the intermediate nodes only have to provide information about the current network state to the end systems, and don´t have to estimate the transmission rate of the flows. The coexistence of flows from OBP and other transport protocols in the same link does not introduce additional problems because the transmission rate of OBP flows is estimated at the sender end system. In this paper we present the new algorithm to estimate the transmission rate of each flow at the end systems. Moreover, we present the evaluation results in fat networks based on NS2 simulations. The results show that OBP can outperform current transport protocols and achieve results as good as XCP (Explicit Congestion Notification Protocol), using a simpler model.