MPTCP Meets FEC: Supporting Latency-Sensitive Applications Over Heterogeneous Networks

Abstract

Over the past years, TCP has gone through numerous updates to provide performance enhancement under diverse network conditions. However, with respect to losses, little can be achieved with legacy TCP detection and recovery mechanisms. Both fast retransmission and retransmission timeout take at least one extra round trip time to perform, and this might significantly impact performance of latency-sensitive applications, especially in lossy or high delay networks. While forward error correction (FEC) is not a new initiative in this direction, the majority of the approaches consider FEC inside the application. In this paper, we design and implement a framework, where FEC is integrated within TCP. Our main goal with this design choice is to enable latency sensitive applications over TCP in high delay and lossy networks, but remaining application agnostic. We further incorporate this design into multipath TCP (MPTCP), where we focus particularly on heterogeneous settings, considering the fact that TCP recovery mechanisms further escalate head-ofline blocking in multipath. We evaluate the performance of the proposed framework and show that such a framework can bring significant benefits compared to legacy TCP and MPTCP for latency-sensitive real application traffic, such as video streaming and web services.Index Terms-TCP, MPTCP, forward error correction, XOR, multipath, congestion control, wireless networks suboptimal [3], [4], with one of the main limiting factors being TCP's loss recovery time. In such scenarios, it is often an option to replace TCP by UDP, at the expense of compromising benefits such as flow and congestion controls. When MPTCP [5] emerged, enabling simultaneous use of multiple network paths by a single data-stream, it had to take operability and deployment in the Internet into account, hence, making MPTCP look like regular TCP from the network's perspective. Although this integration brings many benefits, it also comes with challenges that hinder MPTCP. Particularly, when the underlying network paths are heterogeneous, MPTCP often underperforms TCP especially for certain latency-sensitive applications [6], [7].Next, we will first put MPTCP in perspective with TCP, also mentioning its performance challenges under certain network environments. We will then discuss our motivation for designing a dynamic XOR-based Forward Error Correction (dFEC) inside TCP, and how this can aid multipath transport for heterogeneous paths. Finally, we will summarise the applications chosen for the evaluations and their requirements.

QUIC-FEC: Bringing the benefits of forward erasure correction to QUIC

“…These techniques transmit redundant code to enable the receiver to recover from packet losses without waiting for retransmissions. FEC techniques have already been used in multicast applications [12], [13] or in TCP [14]- [17], but the TCP extensions are difficult to deploy [10].…”

Tuning high flow concurrency for MPTCP in data center networks

“…Considering the continuously increasing demand for mobile communication, literature [38] presents two novel scheduling schemes which are the block estimation (BLEST) scheduler and the shortest transmission time first (STTF) scheduler to guarantee low-latency communication of MPTCP. To improve the performance of latency-sensitive applications over MPTCP in high-delay and lossy networks, literature [39] proposes a new framework using a XOR-based dynamic FEC scheme to reduce the flow completion time.…”

Towards Adaptive Multipath Managing: A Lightweight Path Management Mechanism to Aid Multihomed Mobile Computing Devices

“…Although applying MPTCP to the multihomed mobile computing devices towards multipath data transmission provides numerous potential benefits for data delivery [12][13][14][15][16][17][18][19], the MPTCP path management mechanism is very simple in RFC6824 [7], and this, in turn, leads to MPTCP being vulnerable to the path quality differences of the multiple paths [20]. With the regular path management mechanism, the MPTCP data traffic can be split and assigned to all the available end-to-end paths for concurrent multipath transmission.…”