Emulation and Performance Evaluation of a Transparent Reordering Robust TCP Proxy

The use of multiple paths in core networks for TCP traffic sounds promising as it suggests bandwidth aggregation, fault tolerance through redundancy, high resource utilization efficiency, reduced congestions, and increase in TCP throughput. In order to benefit from all these features, the load balancing approaches at different granularities (per-flow, per-destination, and per-packet) have to be applied. In order to promote use of per-packet load balancing in core networks, we already proposed a transparent TCP proxy called as ORTA (Out-of-Order Robustness for TCP with Transparent Acknowledgment Intervention). ORTA was introduced along with simulation results which were all promising and competing with the nontransparent approaches in the literature. However, network simulations may not reflect the real system performances because of the lack of precise and accurate model of the real systems. In this paper, ORTA is implemented as a netfilter module and emulation test results are presented. The results indicate that ORTA prevents TCP performance degradation caused by TCP packet reorderings. Moreover, ORTA has no degrading impact on TCP performance when packet reordering does not exist.