Injection Time Planning: Making CQF Practical in Time-Sensitive Networking

Time-Aware Shaper (TAS) is a core mechanism to guarantee the deterministic transmission for periodic time-sensitive flows in Time-Sensitive Networking (TSN). The generic TAS requires complex configurations for the Gate Control List (GCL) attached to each queue in a switch. To simplify the design of a TSN switch, a Ping-Pong queue-based model named Cyclic Queuing and Forwarding (CQF) was proposed in IEEE 802.1 Qch by assigning fixed configurations to TAS. However, IEEE 802.1 Qch only defines the queue model and workflow of CQF. A global planning mechanism which maps the time-sensitive flows onto the underlying resources both temporally and spatially is urgently needed to make CQF practical.In this paper, we propose an Injection Time Planning (ITP) mechanism to optimize the network throughput of time-sensitive flows based on the observation that the start time when the packets are injected into the network has an important influence on the utilization of CQF queue resources. ITP provides a global temporal and spatial resource abstraction to make the implementation details transparent to algorithm designers. Based on our ITP mechanism, a novel heuristic algorithm named Tabu-ITP with domain-specific optimizing strategies is designed and evaluated under three typical network topologies in industrial control scenarios. Compared with the Naive algorithm without using ITP mechanism, experimental results demonstrate that Tabu-ITP improves the mapped flow number by 10x and the resource utilization by 65%.