Zigbee’s Dotdot application layer has been ported to the sort-of-rival Thread protocol this week, ahead of a CES that is expected to be rammed full of smart home device announcements. The two alliances say that running the Dotdot app-stack on top of Thread’s networking stack enables the first interoperable IoT language running over an IP-based network.
Both Zigbee and Thread are IEEE 802.15.4-based mesh networking protocols. Zigbee has been in the market for some 15 years, and overhauled itself in the past couple of years to provide a more unified offering – of Zigbee 3.0 and its Zigbee Cluster Library (ZCL), rather than the handful of separate options that were available (Pro, GreenPower, RF4CE, etc). Thread is a much more recent arrival, growing out of Nest-Google but ticking many of the same boxes.
But Thread lacked an application layer, and so often used Zigbee’s – and it seems that this relationship eventually morphed into Zigbee making its application stack portable to other protocols – meaning that you could use the Dotdot application layer for other languages, such as Bluetooth or WiFi, and potentially things like LTE-M or NB-IoT.
“The Thread Group’s vision is to extend IP – the powerful foundation of the internet – to low-power IoT devices. Just like the internet, this vision also requires the industry to put forth open, common protocols so devices from any vendor can work together. Dotdot gives Thread adopters an important option for that open, end-to-end connectivity and interoperability,” said Grant Erickson, president of the Thread Group.
For Thread, expanding its Zigbee integration is an important step towards boosting adoption. Things have been slow-going for a while, but that is something that can be said of the whole smart home market. With Alphabet possibly rolling Nest back into Google, we might see an uptick in Thread evangelism, as Google looks to tackle Amazon’s lead in smart home voice systems – using Thread to flesh out its device integrations and platform offering (although there’s nothing stopping Echo-adopters from doing the same).
The Zigbee Alliance calls Dotdot a universal language for the IoT, but it’s important to make clear that it is not a programming language. Zigbee can be made to work with IP messaging, but Thread is natively IPv6 compatible – which might remove a few head-scratchers from the development process. Both Thread and Zigbee use the same PHY and MAC layer, but Zigbee’s native networking layer is Pro.
Essentially, Dotdot defines how devices connect to networks and how they speak to other devices once they have joined. As long as a device is using Dotdot, it should be able to communicate with all other Dotdot devices on a shared network. While the Zigbee Cluster Library manages this for Zigbee, Dotdot is providing a way to do the same for other protocols – which has obvious benefits when it comes to IoT environments, as it means that WiFi devices should be able to communicate natively with Thread or Zigbee units.
Daniel Moneta, EVP Corporate Development at MMB Networks, and the Marketing Workgroup Chair for the Zigbee Alliance, illustrates the need for why direct communication is so important for the IoT – especially in the home, where tolerance for poor performance is quite low.
Describing a home of around 20 devices, each linked through bridging gateways and different clouds; “just thinking about the engineering calories spent developing all those APIs and then gluing them together just to make a light turn on and off makes me cringe a little. What makes me cringe even more is given the amount of constant change amongst all those interfaces, even with constant effort by every vendor to keep up, at any given time almost every device I have hasn’t worked for a bit (or even a moment). As the number of devices I have goes up, the probability of something being broken at any time approaches 100%. Thanks to my Alexa or Google Home, I now have a happy voice reminding me of exactly what’s broken every time I turn the lights on.”
Once smart homes begin scaling the average number of devices, Moneta’s point grows sharper. Using something like Dotdot across multiple networking protocols should reduce the likelihood that devices end up orphaned on home or business networks. Moneta stresses that the current approach is not scalable, and not something that the market will accept – as a ‘broken’ device will just be thrown in a drawer and forgotten, or thrown in the trash by an irate user.
In theory, Dotdot should enable all those devices to stay connected to all other Dotdot units, preventing them from completely losing their network connections. For developers, it means not having to hire the skills to support multiple protocols or devices, and for those looking to build or sell ecosystems, picking Dotdot should mean that your gateways, thermostats, or lightbulbs will all play nicely together – again, in theory.
“Zigbee and Dotdot are the product of 15 years of innovation by our members, and the experience that comes from over a decade of building successful products,” said Tobin Richardson, the president and CEO of the Zigbee Alliance. “This maturity is why major technology leaders have chosen Zigbee, and Dotdot over Thread now brings that value to new markets. This marks the first of many partnerships come as we extend our application layer across additional networks to accelerate time to market and unify the IoT for all stakeholders.”