I'm Rob Faludi, Chief Innovator for Digi International.
And today, I'm going to give an overview of different mesh networking protocols and the strengths and weaknesses of each based upon your application.
What is mesh networking?
So what is mesh networking? Mesh networking allows you to extend the reach the Internet of Things device network by allowing each device, or node, on your network to act as a router.
Data can then hop from node to node so that radios which are too far apart to hear each other directly can still communicate. In a mesh network, routing is taken care of by the protocol itself and networks can form and fix themselves automatically. In a non-mesh, or point-to-point network, data can be passed between nodes that can hear each other but never to devices that are out of direct range. So for example, if this radio wants to communicate with one of its neighbors, that's no problem. But it has no way to communicate with devices that are too far away.
Here's a quick summary of the difference between point-to-multipoint and mesh networking.
Difference between point-to-multipoint and mesh networking
In a point-to-multipoint network, communications are generally faster and simpler. However, you're limited to the reach of individual radios.
In a mesh network, there is no single point of failure and every radio can communicate with every other radio on the network, no matter how far away they are, as long as there's a valid route. So for example, this radio can talk to this radio through this one up here, but if that one becomes disabled, the network will automatically rebuild a route through another radio so that information can still reach its destination.
Mesh networking though does come at a cost. There's greater latency. In other words, a longer delay between sending and receiving information in some cases and added complexity in putting the network together. So, it should only be used when you're getting a benefit. You may notice that there are multiple different types of mesh networks. We have three on the board here and I'm going to go through them one by one.
Different types of mesh networks
The first is Zigbee. ZigBee uses radios that are in different defined roles. So, there are coordinators which set up the network and then allow routers and end devices to join. Router radios which can support maybe up to 20 or so end devices each and can route data along the network between each other. Finally, end devices that do not route and must join the network through a parent, but have the ability to sleep and pick up messages that are being sent to them automatically when they wake up.
In DigiMesh, all of the nodes in the network can route data and in fact, the whole network can go to sleep and wake up together. So, there are no parent-child relationships and additional routers can be added to extend coverage extremely easily. Routing can be enabled or disabled on individual nodes so the network can be set up to match your application requirements.
A Thread mesh network is built on open standards and IPv6 internet addressing. It creates a secure and reliable mesh with no single point of failure, with simple connectivity, and low-power operation's possible. It also comes with banking class encryption as an option. So, how do you choose?
How to choose the right mesh networking technology?
In simple terms, you can choose ZigBee whenever many nodes on the network are going to be constantly powered, anytime inter-operation between different manufacturers is a requirement, when you need flexible security options, and also, if you want special routing set up. For example, many-to-one routing when you have a large number of end devices but they're all routing to a central aggregator or gateway node, typically to pass information to the internet.
Choose DigiMesh when most of your devices need to be battery-powered, you want really simple provisioning, and routing on your network is extensively between peers.
Choose Thread whenever you're going to have extensive interactions with the internet, anytime dynamic reconfiguration and optimization is needed, anytime multiple routes to the internet are desired. You can see that while all mesh networking technologies, and in fact, point-to-multipoint, can be connected to the internet with a gateway, in the case of Thread, you can have multiple gateways or, in Thread terms, "boarder routers," meaning there's no single point of failure.
Thread is a brand new protocol, so keep in mind that you're taking on the inherent risks of new technology. This has been a very brief overview but there's a lot more to know. To learn more, Digi International has a wonderful library of documentation along with many experts that can help you select the perfect network for your applications.