SACK+/CHOKe+: making a tradeoff between Efficiency and Fairness in Satellite Networks

Making a satellite system a fully functional Internet router has challenges because the characteristics of satellite communication networks are mismatched to most common Internet link technologies in several important ways. Under some error conditions, "multiple segment losses within a single window" happens frequently and traditional selective acknowledgment (SACK) implementation may force the TCP sender to retransmit packets that have already been received successfully by the receiver. This paper puts forward a proposed SACK+ implementation to prevent unwanted retransmission in satellite communication networks. On the other hand, in order to provide a fair bandwidth allocation to each of n flows that share the outgoing link of a congested router and to overcome low efficiency when the number of high-volume sources is small, we propose CHOKe+ (choose and keep for responsive flows, choose and kill for unresponsive flows+) as the fair queuing policy in satellite communication networks. We show that the proposed implementation of SACK+/CHOKe+ makes a good tradeoff between "efficiency" and "fairness" by NS2 simulations.