About Thread Network Protocol


What is the Thread Network Protocol and why does it Matter? Tom gives a brief overview of it’s history and current use.

Featuring Tom Merritt.



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I’ve been hearing about new smart home devices that use Thread

I’ll be honest after Zigbee, Z-Wave, and the rest I’m kind of skeptical of yet another new smart home protocol.

Do we really need Thread?


Don’t be. Let’s help you Know a Little More about the Thread network protocol.

Thread is a low-power networking protocol meant for use by Internet of Things devices. For most of us that means doorbells, cameras, window sensors and the like.
Thread operates a self-healing mesh network. The oversimplified explanation of that is that each device on a mesh network can talk directly to every other device no matter who made them. Essentially each Thread device is an access point. So you don’t need a special hub.
The self-healing part means when the network runs into trouble there’s an algorithm (like Shortest Path Bridging or TRILL) to help figure out a route around the trouble.
While Thread uses a mesh network, it does require at least one “border router” that can send and receive data between the Thread devices and the internet when necessary. But that doesn’t mean you have to have a single point of failure, because you can have more than one border router. For instance, you could set up a Google Nest WiFi device and say, an Apple TV, to both be border routers.
A Thread network can support up to 250 or so devices with multiple hops. That’s not a lot of devices compared to Zigbee’s 65,000, but Thread makes it up in flexibility and 250 will be enough for a while. (You thought I was going to say 250 ought to be enough for anybody, didn’t you? Au contraire.) Hopefully the standard can expand beyond 250 by the time we get smart dust or whatever application makes 250 seem ridiculously small.
Let’s take a moment and talk for people who speak in standards acronyms. If this doesn’t make sense to you, don’t panic, I’ll translate in a second. Thread makes use of IPv6 – which is a way to assign a unique number to every device on a network. Something not possible under the older IPv4 protocol. Thread uses 6LoWPAN which stands for IPv6 over Low-Power Wireless Personal Area Networks. Basically, a system for assigning those IP addresses. That system relies on the power-efficient IEEE 802.15.4 wireless protocol on the 2.4 GHz spectrum. Some of you may recall that the Zigbee smart home protocol also uses that same setup. But Zigbee does not use IPv6 so it requires a hub.
OK here’s another way of putting all that. With Thread, you don’t need a special hub and each device can be uniquely identified.
And it’s similar to Zigbee but not the same. For instance, Apple supports Thread.
But keep in mind that almost any device that supports IEEE 802.15.4– like Zigbee devices do– could become a Thread device with a software update, including Zigbee devices. Not all devices will do that, but they could.
OK a few more cool things about Thread’s implementation of all these underlying standards.
Thread is low-power so devices can run on coin-cell batteries for a few years.
And because it doesn’t need a hub, and due to a few other advantages of its implementation, the protocol is low latency. You generally see near instant response times.
And Thread is also secure. It uses AES-128 encryption on every connection between every device. And when you add a device to the network, it uses Password-Authenticated Key Exchange, so the network key is never transmitted where it could be eavesdropped on by an attacker. You use a device already in your Thread network, like your phone, and a password that is printed on a manual or box that came with the new device. Sometimes it’s just a QR code you scan with your phone. That process is used only to authenticate the device on your Thread network.
And I can hear at least one of you saying “The password is on the box!” That’s a one time use password to set the device up. Kind of like a public key It would only be useful to somebody already inside your network, in which case you have bigger problems.
So the short version of this is that everything is strongly-encrypted from the moment you join onward.
OK, that sounds great but who’s running this standard? How can we be sure anybody will use it? Let’s start at the beginning.
Nest started developing Thread in 2011. Google bought Nest in January, 2014 and 6 months later formed the Thread Group Alliance and officially proposed the Thread Protocol. Apple joined the Thread Group in 2018 and released its first Thread product, the Home Pod Mini (which acts as a border router) in 2020.
There are now more than 50 members of The Thread Group. The top level of membership is sponsors, of which there are 13, including Apple, Google, Amazon, Lutron, NXP, Nordic Semiconductor, OSRAM, Qualcomm, Samsung’s SmartThings, Siemens, Silicon Labs, Somfy and Yale.
The Thread Group is not-for-profit and maintains the protocol and licenses it under a royalty-free program to companies who agree to certain terms. The group also issues certifications of course. And Google operates an open source version of Thread called OpenThread under the BSD 3-Clause license.
And Thread is tied in with a broader interoperability effort called Matter.
The Matter project which is led by the Connectivity Standards Alliance, including Google, Apple and Amazon, adopted Thread along with WiFi and Bluetooth Low Energy, as one of its supported protocols. Matter itself will also use WiFi and Matter controllers (aka hubs) which will expand the interoperability of Thread devices.
And it’s worth pointing out that because it’s based on an IEEE standard and uses IPv6, Thread is application agnostic. It’s not limited to a particular manufacturer. Because it uses 2.4 GHz, it won’t face restrictions in parts of the world that limit other parts of the spectrum.
All right but there must be some down sides to Thread.
Of course.
It can’t send a lot of data. That’s why Matter also supports WiFi. Thread is for low data rate uses. And it’s not meant for long range either. A Nordic Semiconductor study found Thread’s range was about the same as Zigbee’s, at around 200-300 meters. That’s why Matter supports Bluetooth Low Energy which has a long-range implementation that can reach 756 meters.
In the end, the thing to know about Thread is that it offers faster responses, improved reliability and interoperability and better security while using less power. So if you’re picking between two smart home devices that are pretty close and one supports Thread, you might want to pick the one with Thread.
In other words, I hope you Know A Little More about Thread.