Connectivity Framework 1: Introduction
1.1 PURPOSE
The IIoT landscape is replete with proprietary connectivity technologies and specialized connectivity standards optimized for a narrow set of domain-specific use cases in vertically integrated systems. These domain-specific connectivity technologies, though optimal in their respective domains, can be a hindrance to the sharing of data, designs, architectures, and communications essential to creating new value streams and unlocking the potential of a global IIoT marketplace. The overarching goal of IIoT connectivity is to unlock data in these isolated systems(“ silos”) and enable data sharing and interoperability between previously closed components and subsystems( brownfield) and new applications( greenfield), within and across industries.
This document maps the rich landscape of IIoT connectivity. It clarifies the IIoT connectivity stack, defines an open connectivity reference architecture, and helps practitioners navigate their way to categorize, evaluate, and determine the suitability of a connectivity technology for the system at hand. Specifically, it addresses the following questions:
• What connectivity layers to expect for IIoT?
• What core functions to expect from each layer?
• What are the typical considerations and trade-offs at each layer?
• How to open up communication to participants using a domain-specific connectivity technology?
• What is expected from core connectivity standards?
• How to categorize a given connectivity technology?
• How to evaluate a given connectivity technology?
• How to determine suitability of a connectivity technology against system requirements?
• How to determine the most appropriate core connectivity standard?
• What are the most suitable core connectivity standards for a particular( sub) system?
1.2 SCOPE
The interoperability layers of an IIoT system are hourglass shaped. The top is a wide spectrum of data models and functions specific to a particular industry and the“ neck” is the“ internet” network layer common across industries, as shown in Figure 1-2. Connectivity provides the basic data-sharing mechanisms to support the higher-level functions such as Distributed Data Interoperability and Management as a crosscutting function( semantic interoperability, see Industrial Internet Reference Architecture 1).
The neck of the hourglass in Figure 1-2 is the starting point— it is the“ internet” in“ IIoT”. But the connectivity layers above the neck are not well understood, so we focus on the connectivity functions and considerations above the“ internet” networking layer for building IIoT systems.
1
See [ IIC-IIRA2015 ] IIC: PUB: G5: V1.0: PB: 20170228- 9-