Recent Acknowledgement Support for ns-3 TCP

Recent Acknowledgement (RACK) is a TCP packet loss detection technique proposed by Google. It uses the notion of time to detect packet losses instead of packet or sequence counting approaches like Fast Retransmit and other non-standard techniques. RACK algorithm is described in an Internet Draft in the TCP Maintenance Working Group (tcpm) at IETF and is the de facto loss detection technique since Linux 4.4. However, to the best of our knowledge, there does not exist a model to study RACK using network simulators. Network simulations provide flexibility to extensively evaluate the upcoming network protocols without resorting to complex real-time experiments. In this paper, we propose the design, implementation and validation of a new model for RACK in ns-3. We evaluate RACK by comparing its performance with Fast Retransmit and verify that the model in ns-3 exhibits key attributes of RACK.