Isolating SDN Control Traffic with Layer-2 Slicing in 6TiSCH Industrial IoT Networks

TL;DR

This paper introduces a Layer-2 slicing method using 6TiSCH tracks to isolate SDN control traffic in industrial IoT networks, ensuring deterministic, low-latency control communication and preventing interference with data flows.

Contribution

It proposes a novel use of 6TiSCH tracks to isolate SDN control traffic, improving performance and determinism in constrained IoT networks.

Findings

Tracks effectively isolate SDN control traffic from data flows.

Network slicing reduces SDN overhead impact on application performance.

Deterministic, low-latency SDN communication is achievable with tracks.

Abstract

Recent standardization efforts in IEEE 802.15.4-2015 Time Scheduled Channel Hopping (TSCH) and the IETF 6TiSCH Working Group (WG), aim to provide deterministic communications and efficient allocation of resources across constrained Internet of Things (IoT) networks, particularly in Industrial IoT (IIoT) scenarios. Within 6TiSCH, Software Defined Networking (SDN) has been identified as means of providing centralized control in a number of key situations. However, implementing a centralized SDN architecture in a Low Power and Lossy Network (LLN) faces considerable challenges: not only is controller traffic subject to jitter due to unreliable links and network contention, but the overhead generated by SDN can severely affect the performance of other traffic. This paper proposes using 6TiSCH tracks, a Layer-2 slicing mechanism for creating dedicated forwarding paths across TSCH networks, in order to isolate the SDN control overhead. Not only does this prevent control traffic from affecting the performance of other data flows, but the properties of 6TiSCH tracks allows deterministic, low-latency SDN controller communication. Using our own lightweight SDN implementation for Contiki OS, we firstly demonstrate the effect of SDN control traffic on application data flows across a 6TiSCH network. We then show that by slicing the network through the allocation of dedicated resources along a SDN control path, tracks provide an effective means of mitigating the cost of SDN control overhead in IEEE 802.15.4-2015 TSCH networks.