Delay-Guaranteeing Admission Control for Time-Sensitive Networking Using the Credit-Based Shaper

Abstract

With real-time communication being a key part of the fourth industrial revolution, the need for Quality of Service (QoS) in industrial networks is gaining increasing importance. Time-Sensitive Networking (TSN) faces this need, for example, by introducing new scheduling mechanisms. The Credit-Based Shaper (CBS) has been introduced to TSN to offer low delays for multiple traffic classes by applying rate limitations. Currently, flows are reserved decentrally in CBS networks using a Stream Reservation Protocol (SRP). In contrast, the new TSN standard IEEE 802.1Qcc allows for a centralized architecture to favor short reconfiguration latencies. However, no online admission control scheme which offers safe delay bounds has been proposed for this central architecture. To close this gap, we propose two models for admission control in TSN networks using CBS. Both models offer deadline-guaranteeing flow allocation, including routing and prioritization of flows, and configure forwarding devices while eliminating packet loss. Our models utilize the mathematical framework of Network Calculus to calculate worst-case flow delays and buffer sizes. We show how our models allow for more reservations than the decentralized standard approach by improved resource utilization. We validate our models both in synthetic and industrial network scenarios. Additionally, we compare the effects and parameters of our two models, providing guidance on when to choose them.

On the Validity of Credit-Based Shaper Delay Guarantees in Decentralized Reservation Protocols

“…In future research, we aim to investigate centralized and decentralized configurations within the same network, by the incorporation of the central approach presented in [19]. Furthermore, we intend to optimize the per-hop delay bounds to maximize the number of successful reservations through the…”

“…All of these works analyze the flow delays for static flow reservations, while we derive local upper bounds which remain valid even after new flow registrations. In [19], Maile et al use NC for CBS networks for the configuration of delay guarantees with a central network controller while the network is running. Contrary, our paper presents a solution for decentralized network setups.…”

“…These can be calculated based on the TSpecs from SRP and RAP, as shown in Eq. (19). In addition to that, the term Δ𝑑 𝑓 can be obtained by using the accumulated latency fields in both SRP and RAP.…”

Hierarchical Cross Traffic Scheduling Based on Time-Aware Shapers for Mobile Time-Sensitive Fronthaul Network

“…Feng et al [25] designed a specific shaping mechanism based on flow QoS by combining the strict priority algorithm and the CBS algorithm, in which the CBS algorithm is responsible for shaping ordinary flows. Maile et al [26] proposed a scheme by combining CBS with TAS, which effectively meets the QoS requirements of industrial automation scenarios. Though these scheduling schemes can effectively reduce the delay, there exist jitters of high-priority streams caused by the continuous transmission of low-priority streams.…”

Research on traffic scheduling algorithm and parameter optimization based on load balancing in time-sensitive network

“…Because SR traffic packets are large and have certain delay requirements, it is necessary to reserve a certain amount of bandwidth for them in the scheduling process. The commonly used method is to use the size of the packets transmitted by SR traffic per unit of time as the reserved bandwidth [4] . This reserved bandwidth calculation method is simple, but it does not consider the constraint of SR traffic cutoff time.…”