PPoS: A Novel Sub-flow Scheduler and Socket APIs for Multipath TCP (MPTCP)

Multipath TCP (MPTCP) can exploit multiple heterogeneous interfaces available at the end devices by establishing concurrent multiple connections. MPTCP is a drop-in replacement for TCP. This makes MPTCP an attractive choice for various applications. In recent times, MPTCP is finding its way into constrained devices such as robots and Unmanned Aerial Vehicles (UAVs). For these devices, it is critical to provide better Quality of Service (QoS) to control data than user data. In this paper, we have presented Primary Path only Scheduler (PPos), a novel sub-flow scheduler, for constraint devices such as UAV s and robots where it is efficient to segregate data on different links based upon type of data or QoS requirements to improve reliability and error resilience. We have proposed a new MPTCP kernel data-structures and algorithm to make the sub-flow priority persistent across sub-flow failures. We have introduced several new socket APIs to control the sub-flow properties of MPTCP at the application layer and also for providing the fine grained control over the behaviour of PPoS. These APIs can help modifying the MPTCP behaviour for each socket/application individually rather than changing the behaviour system wide. The proposed scheduler and the socket APIs are extensively evaluated in an Mininet based emulation environment. We have also integrated PPoS and Socket APIs with Robot Operating System (ROS) and measured their performances on Raspberry-Pi based testbed as well.