Great discussion! We’re still working on documentation, but here’s some details to get us started:
Gateways, Repeaters & Endpoints
Particle Mesh devices can play different roles in a mesh network: gateways, repeaters and endpoints. Repeaters make up the backbone of the mesh network. They are always on and can be trusted to relay messages across the network. Endpoints are typically sensors or actuators. As oppose to repeaters, they are not required to always be on and therefore can be battery-operated and sleepy. They pair with a nearby “parent” repeater, who queue messages on their behalf when a child endpoint is asleep. Gateways are special types of repeaters that have a backhaul back to Particle’s Device Cloud. The devices we announced today can play different roles, depending on how their software is configured:
- Argon: Gateway, Repeater or Endpoint
- Boron LTE/2g3g: Gateway, Repeater or Endpoint
- Xenon: Gateway (with Ethernet FeatherWing,) Repeater or Endpoint
Theoretical and Practical network sizes
At launch, we’ve developed a lot of the software needed for Particle Mesh. However, we have a lot more development to go before we ship. Some of this development will impact the total network size possible.
A repeater can support a finite number of children endpoints and therefore the total network size is dependant on the number of repeaters/gateways in a network. The total network size increases with the number of repeaters/gateways in a network. A network can support a finite number of repeaters so therefore there is a finite maximum network size. A network can support multiple gateways which allows for redundant connections to the Particle Device Cloud.
When planning your network, we recommend you first start thinking how many sensors and actuators you’re deployment might need. That will govern how many repeaters are needed for the network. Then decide how many gateways you need to guarantee connectivity.
Note: while endpoints are ideal for sensors and actuators, you can attach sensors and actuators to gateways and repeaters because they share the same capable MCU as the Xenon, which might save some cost on endpoints.
Particle Mesh & Thread
Particle Mesh is based on the Thread networking protocol. As someone noted, Particle Mesh uses OpenThread and openthread.io is the best place to learn more about the technical details of OpenThread & Thread. While you’re reading their site, note that Particle Mesh uses more consumer-friendly terms for Thread roles. For reference:
- Particle Mesh Endpoint = Thread End Device
- Particle Mesh Repeater = Thread Router
- Particle Mesh Gateway = Thread Border Router
Thread networks support a theoretical limit of 32 routers, each with 512 children. Therefore, a single Thread network could reach 16,384 devices. However, practical limits like memory on device will impact real-world numbers. As a baseline, the Thread Group demonstrated a network of 250 devices in a lab environment. We’ll improve our software over time and in the months before we ship but we’re haven’t finalized our evals. We intend to support (at minimum) a network of 1-2 gateways & 3-5 repeaters - with 10 endpoints each. That brings the total to 55ish devices in a network for this first release.
That’s a lot for now, phew! Hope this helps! Keep the questions coming 