The devices connect to each other either in a star, tree or meshed network scheme. The network manages the end devices autonomously.
With the star scheme, all devices communicate via a central node. However, this connection point is susceptible to collisions, which can disrupt or delay data transmission. In the tree structure, communication also starts from the central node and spreads hierarchically from the inner to the outer point, similar to the ramification of a tree crown.
The most reliable of these networks is the mesh network, as it sends data signals from any transmitter to any receiver, with each node acting as a router for the neighbouring points. Several data paths are always possible if one of the intermediaries fails.
Control
For the use of the ZigBee standard, a Smart Home center is required. For this you need a ZigBee Bridge, which acts as an interface between e.g. Smartphone and end devices. Users who prefer to control their home via HomeKit, Google Home or App, however, do not benefit much from Echo Plus. You should rather use ZigBee control centers from other manufacturers, e. g. EnOcean-hue-DALI Bridge.
There are also ZigBee-compatible remote controls with which, for example, lamps or thermostats can be conveniently controlled from the sofa. (e.g. the ZigBee remote control from PUR-LED)