Wireless / Fieldbus

Will IPv6 Give ISA100.11a a Leg Up?

The Recent Wireless Sensor Network Study by IDtechEx Anticipates the WSN Market Will Be over $2 Billion in 10 Years

By Ian Verhappen

Besides giving us another acronym to add to our repertoire, will the Internet Protocol, version 6 (IPv6) in the industrial sector make "Ethernet everywhere" extend to field sensors? The ISA100 development team certainly thinks and hopes so.  With the 128-bit addresses, IPv6 supports 216 or 3.4 x 1038 addresses. When you consider that we continue to use all the techniques that are allowing us to extend IPv4, this number may not equal infinity, but it is getting closer.

As a result, it should be possible to connect to an almost limitless number of sensors—allowing us to measure anything, anywhere, anytime. Active and passive radio frequency identification (RFID) sensors are both small enough and low enough in power to enable anything-anywhere sensing.

The recent Wireless Sensor Network (WSN) study by IDtechEx anticipates the WSN market will be over $2 billion in 10 years. The increasing ubiquity of RFID-sensor-enabled devices and their shrinking cost will contribute to the growth of  the Internet of Things (IOT) and 6LoWPAN ("diet" IPv6) will likely play a role in connecting these devices to the larger network.

The Internet Engineering Task Force's (IETF) request for comments (RFC) for the 6LoWPAN working group defines encapsulation and header compression mechanisms that allow IPv6 packets to be sent and received via IEEE 802.15.4-based networks, which coincidentally are the same networks used by industrial wireless protocols WirelessHART, Bluetooth and ISA100.11a. ISA100.11a is the only one of these standards to incorporate IPv6 directly as part of its network layer and transport layer definitions.

Because ISA100.11a supports up to 216 devices, the ability to create and participate in subnets is an important tool for managing the network. ISA100.11a's  support for multiple subnets will enable sensors to be grouped together much like a VLAN for traffic and network management, while also breaking the network into zones for security reasons.

ISA100.11a includes support for subnet-level mesh, as well as backbone-level routing. Different parameters and requirements need to be adopted and fulfilled in different routing scenarios, such as when performing address translation when the routing level changes. Doing so also has an energy-efficiency benefit, since 16-bit address deployment in subnet routing consumes much less energy and bandwidth than using a 128-bit global address.

Stringent timing accuracy and high reliability are critical components of industrial control systems. ISA100.11a includes the ability to configure a field backbone into the network for the purpose of latency minimization, additional bandwidth and higher quality of service. The backbone router that acts as an interface between the field and backbone networks, typically by connecting to the field network gateway, encapsulates network layer messages, and transmits them through the protocol stack of the backbone network to the final destination. This "final destination" could be a gateway for the host with its associated applications, or another I/O device placed at the opposite end of the backbone because the backbone is "the Internet." With appropriate security, the other end could be practically anywhere.

ISA100.11a and the recent demonstration at Petrobras in Brazil give IPv6 the advantage of seamless end-to-end routing with "anything anywhere" effectively in a single environment. This is the reason that, though behind now, the suite of ISA100 standards has a good chance of being the "come-from-behind winnah at the wire" in the wireless standards race.

For a number of reasons, wired connectivity to field sensors has more roadblocks than those of the wireless world envisioned by ISA100.IPv6 and ISA100 make the Industrial Internet of Things, or I2OT, one step closer to reality.