Multi-Stream Gate Control of Time Aware Shaper for High Link Utilization

Ultra-low latency (ULL) data transmission is essential for many network applications. The IEEE 802.1Qbv Time-Aware Shaper (TAS) is a typical mechanism for providing ULL data transmission in bridged networks. All TAS enabled nodes must be time-synchronized and their gate time schedule in the gate control list (GCL) must be pre-configured considering the data arrival time and the maximum burst size. Consequently, the bandwidth utilization is drastically deteriorated if the data size becomes small, because no data can be forwarded until the state of the gate changes. Although the underutilization of link bandwidth can be addressed with gate shrunk (GS-)TAS which enables runtime reconfiguration of the GCL using a GS-frame at the end of an express traffic. However, the states of gates cannot be appropriately controlled with the existing scheme if there are many express streams. To address this issue, this paper proposes a concept of multi-stream gate control for TAS. The proposed idea enables runtime reconfiguration of the GCL to avoid the reduction in bandwidth utilization irrespective of the burst size and the number of streams. The performance of the proposed scheme was confirmed with computer simulations.