Page 29 - ITUJournal Future and evolving technologies Volume 2 (2021), Issue 1

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 1

RECONFIGURATION ALGORITHMS FOR HIGH PRECISION COMMUNICATIONS IN TIME
SENSITIVE NETWORKS: TIME‑AWARE SHAPER CONFIGURATION WITH IEEE 802.1QCC

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Ahmed Nasrallah , Venkatraman Balasubramanian , Akhilesh S. Thyagaturu , Martin Reisslein , Hesham ElBakoury 5
1,2,3,4 Arizona State University, School of Electrical, Computer, and Energy Engineering, 650 East Tyler Mall, Tempe, AZ
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85287‑5706, USA, Intel Corporation, 5000 W. Chandler Blvd., Chandler, AZ 85226, USA, Formerly with Huawei
Technologies Co., now Self‑employed, 4211 Norwalk Dr., CC‑102, San Jose, CA 95129, USA
NOTE: Corresponding author: Martin Reisslein, reisslein@asu.edu
Abstract – As new networking paradigms emerge for different networking applications, e.g., cyber‑physical systems, and
different services are handled under a converged data link technology, e.g., Ethernet, certain applications with mission critical
traf ic cannot coexist on the same physical networking infrastructure using traditional Ethernet packet‑switched networking
protocols. The IEEE 802.1Q Time Sensitive Networking (TSN) Task Group is developing protocol standards to provide de‑
terministic properties, i.e., eliminates non‑deterministic delays, on Ethernet based packet‑switched networks. In particular,
the IEEE 802.1Qcc, centralized management and control, and the IEEE 802.1Qbv, Time‑Aware Shaper (TAS), can be used to
manage and control Scheduled Traf ic (ST) streams with periodic properties along with Best‑Effort (BE) traf ic on the same
network infrastructure. We investigate the effects of using the IEEE 802.1Qcc management protocol to accurately and pre‑
cisely con igure TAS enabled switches (with transmission windows governed by Gate Control Lists (GCLs) with Gate Control
Entries (GCEs)) ensuring ultra‑low bounded latency, zero packet loss, and minimal jitter for ST TSN traf ic. We examine both
a centralized network/distributed user model (hybrid model) and a fully‑distributed (decentralized) 802.1Qcc model on a
typical industrial control network with the goal of maximizing the number of ST streams.
Keywords – Cyber‑physical systems, low‑latency traf ic, protocol adaptation, recon iguration, Time Sensitive Networking
(TSN).
1. INTRODUCTION added or removed. Or, nodes may inject additional
traf ic lows or traf ic lows may terminate, or the latency
1.1 Motivation requirements of lows may change dynamically. Such
IEEE 802.1 Time Sensitive Networking (TSN) provides a dynamic changes have been included in the use cases
standardized framework of tools for providing determin‑ de ined by the IEC/IEEE 802.1 TSN TG [10, 89]. In a
istic Ultra‑Low Latency (ULL), e.g., for industrial control typical industrial environment, sensors that periodically
applications, automotive networking, smart grid applica‑ or sometimes sporadically send ambient measurements
tions, and avionics communication systems [11, 22, 30, to a local gateway require certain Quality of Service
34, 57, 63, 88]. In particular, the IEEE 802.1Qbv Time (QoS) guarantees [6,16,31,42,64]. In such a volatile and
Aware Shaper (TAS) has received extensive attention as dynamic environment, new machinery that requires pri‑
a key tool for achieving a deterministic ULL network ser‑ oritized execution (e.g., emergency cooling procedures
vice. The TAS operation requires careful planning of the or maintenance tasks for network traf ic tests) may be
synchronized time cycles [79, 85, 91] and the gate times brought onto the factory loor. To deal with such sce‑
that are allocated to the Scheduled Traf ic (ST) and the narios, the Time‑Aware Shaper (TAS) Gate Control Lists
unscheduled Best‑Effort traf ic (BE). The TAS parameter (GCLs) in coordination with the Network Management
settings specifying the timing characteristics (cycle time, Entities (NMEs), e.g., Centralized Network Con iguration
gate slot allocations) are also commonly referred to as the (CNC), have to adapt to changing environment conditions
Qbv schedule or the TAS schedule. For a given static net‑ by judiciously applying recon iguration such that stream
working scenario, the TAS operation with a properly con‑ deadlines and QoS are satis ied.
igured Qbv schedule can ensure the deterministic ULL re‑ Generally, in such dynamic networking scenarios, apply‑
quired by demanding industrial and automotive applica‑ ing only admission control will clearly guarantee (in ac‑
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tions [8,27,40,59,62,77,84] . cordance with a traf ic shaper) the QoS metrics of the ad‑
Modern network scenarios often involve dynamic mitted lows. However, for a given static network con ig‑
changes with varied use cases, such as changes in the uration, the total number of admissible streams may be
network nodes and network topology, or the traf ic well below the number of streams that seek network ser‑
pattern. For instance, nodes or links may be dynamically vice. Therefore, adding a dynamic recon iguration strat‑
egy to manage and con igure the network appears to be
1 A preliminary abridged version of this study appeared in the IEEE
Globecom 2019 workshop paper [60]. This journal article substantially a plausible and attractive solution that intuitively should
extends the prior workshop paper, as explained in Section 1.2. lower capital and operational expenditures as it mitigates

© International Telecommunication Union, 2021 13