During the early days of networking, the term “gateway” essentially meant hardware capable of protocol translation. As the internet evolved, routers and switches became the dominant network gears, and we almost forgot about gateways, until recently, with the advent of the Internet of Things (IoT).
Today, it’s almost impossible to design an IoT use case without using a gateway. Depending on the scope of the architecture, there could be several gateways, each performing a different role. No wonder, the rapidly expanding IoT gateway market is expected to ship more than 139 million units by 2021. These findings are from ABI Research’s M2M/IoT Routers and Gateways, QTR 3 2019 report.
What made gateways so crucial for IoT?
At its simplest form, an IoT gateway may just be a piece of hardware or software to collect and aggregate data from I/O devices like sensors. The gateway then communicates the data to servers either in local data centers or in the cloud. In such a simplified context (e.g., in MQTT), the gateway functions as a “broker”.
However, in a marketplace where Gartner® Inc. expects 20 billion IoT devices to go live by 2020, and vendors are touting various gateway capabilities, it’s easy to confuse the role of IoT gateways. So let’s size up the essential functions of gateways in IoT.
The most common usage of IoT gateways is as edge devices, to the extent that a few vendors market them as ‘edge’ gateways. As shown in Figure 1, the edge gateway can either directly connect to IoT field equipment (sensors, actuators, etc.) or through programmable logic controllers (PLCs), distributed control system (DCS), industrial control system/supervisory control and data acquisition (ICS/SCADA) etc. which aggregate field data. These gateways need to support a wide variety of I/O interfaces, including wired, wireless, and even serial connections (e.g., RS-232).
In such scenarios, gateways serve two main objectives:
Figure 1: Gateways are used at multiple levels in IoT architectures (Source: Practical Industrial Internet of Things Security)
But a more critical role of edge gateways is localizing on-premise computing. Each bit of data sent to the cloud costs money, bandwidth, and latency. Instead of sending all data to the cloud, edge gateways distribute the processing workload among its native CPUs, or across fog nodes, and sends only meaningful data to the cloud.
Edge gateways are usually equipped with processing horsepower (e.g., Dell uses Intel’s dual-core Atom processors), and software intelligence that includes filtering, analytics, and secure elements.
In industrial companies, legacy equipment is a major barrier to adopting IoT. Due to the long lifespan of industrial equipment, instead of replacing legacy gear, a viable option is to integrate legacy gear in Industrial IoT (IIoT) architectures. But how?
Some of the common challenges with legacy products are they:
To ease IoT adoption in brownfield scenarios, or when new software is introduced to an information technology environment where legacy systems exists, IIoT gateways fill in those gaps as they can translate proprietary protocols, clean incoming data, add context to data, and act as a “proxy” to facilitate firmware updates, data access, and perform other security functions.
In industrial sites, network segments typically use different proprietary protocols. Over time, industrial information systems (i.e., data historian, asset manager, manufacturing execution systems, and so on) began to use variants of IP and Ethernet standards. However, these variants support only specific industry verticals. For example, power utilities use DNP3, DC-BUS connectivity protocols, while building automation relies on MODBUS, DAC-Net, etc.
This impacts interoperability across verticals. For example, in a smart city project, both building automation and utilities must interconnect. Converging connectivity across different verticals is another critical gap gateways fill in. They can also interconnect disparate networks within an industrial site.
At the high-end of the spectrum, IoT gateways serve as an interface between on-premise deployments and the cloud. These gateways run complex analytics algorithms and machine learning models on incoming data, handle factory automation, execute identity and authentication services, predictive analytics, etc. without cloud contact. These gateways often blur the line between gateways and IoT platforms.
IoT gateways include both software and hardware components. The software can run on dedicated or virtualized platforms. The software stack implements different functionalities e.g., protocol translation, data processing, storage, aggregation, and analytics.
As IoT applications evolve, so will the role of IoT gateways. To future-proof innovations, designing platform-agnostic gateway software is a fundamental imperative. Using platform-agnostic gateway software helps to avoid vendor lock-in and allows you to easily supplement new features. AWS Greengrass and Microsoft® IoT Edge are examples of software-agnostic edge gateways.
Because gateways are exposed to outdoor conditions, it is important to design gateways for the extreme. Consequently, the hardware needs to be tamper-resistant and support a wide range of operating temperatures. Gateways with a ‘fanless’ design require less power and are suitable for resource-constrained settings.
As an essential component in IoT architectures, the market for IoT gateways is fast expanding. Major players include HP Enterprise, Intel®, Cisco, Dell, Fujitsu, Microsoft, IBM, Red Hat, Oracle, VMware, Huawei, Pivotal, among others.
With new IoT connectivity technologies and standards, the industry is well-positioned to roll-out newer gateways serving newer roles. It is indeed a great time to innovate and implement newer gateway electronics and software.
Sravani Bhattacharjee has been a Data Communications technologist for over 20 years. She is the author of “Practical Industrial IoT Security,” the first released book on Industrial IoT security. As a technology leader at Cisco till 2014, Sravani led the architectural planning and product roadmap of several Enterprise Cloud/Datacenter solutions. As the principal of Irecamedia.com, Sravani currently collaborates with Industrial IoT innovators to drive awareness and business decisions by producing a variety of editorial and technical marketing content. Sravani has a Master's degree in Electronics Engineering. She is a member of the IEEE IoT Chapter, a writer, and a speaker.