Zigbee is a low-power mesh protocol on top of the IEEE 802.15.4 radio, used in the 2.4 GHz band by most smart-home devices (sensors, bulbs, plugs, switches).
Three device types
| Type | Does | Typical devices |
|---|---|---|
| Coordinator | forms the network (channel, PAN ID, extended PAN ID, security), exactly one per network | USB adapter or gateway |
| Router | relays traffic for others, stores messages for its sleeping children, lets new devices join; may not sleep | mains-powered bulbs, plugs, dedicated routers |
| End device | does not route, may sleep, talks only through its one parent | battery sensors, remotes, buttons |
Routers must stay awake, so battery devices are normally end devices. Mains power alone doesn't guarantee that a device routes, so check the device's specification.
How the mesh behaves
- Messages hop over routers, so coverage grows with every router you add.
- An end device's parent is the coordinator or a router. If that parent goes offline, traffic to its children stops until they time out and look for a new parent.
- Some devices (Zigbee2MQTT names Xiaomi as an example) never look for a new parent and stay isolated until re-paired.
Zigbee vs Thread
Both use the same 802.15.4 radio technology, but they are different protocols:
- Zigbee defines the whole stack including how devices are controlled (clusters).
- Thread is an IPv6 mesh network only; control comes from Matter or Apple HomeKit on top, and a border router connects it to Wi-Fi/Ethernet.
Devices of one protocol don't join a network of the other.
Where to go next
- Choosing a coordinator and placing it (interference matters more than most people expect).
- Picking a channel that avoids your Wi-Fi.
- Building the mesh with routers before pairing battery devices.