2: ZigBee Topologies > Star Topology

Star Topology

The Star topology is the simplest and most limited of the possible ZigBee topologies. A Star network consists of a Co-ordinator and a set of End Devices. Each End Device can communicate only with the Co-ordinator.

Therefore, to send a message from one End Device to another, the message must be sent via the Co-ordinator, which relays the message to the destination. This is illustrated in the animation below.

	A Router can be used in place of an End Device in a Star network, but the message relay functionality of the Router will not be used -only its applications will be relevant.

A disadvantage of this topology is that there is no alternative route if the RF link fails between the Co-ordinator and the target device. In addition, the Co-ordinator can be a bottleneck and cause congestion.

	To implement a Star network, it is not necessary to use the ZigBee network layer, since a star network topology is provided by the IEEE802.15.4 layer: If the ZigBee network layer is not used, the application program in the Co-ordinator is responsible for relaying messages. If the ZigBee network layer is used, the Co-ordinator passes messages to their destinations transparently to the application program.

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