Packet routing requires a lot of processing overhead
ZigBee devices are designed to be very small
Equipped with low-speed, power-efficient CPUs
In a ZigBee PAN, only the devices that perform routing or are coordinators incur overhead
802.15.4 standard favors battery-powered devices
Does not prevent devices from being connected to another power source
ZigBee must maintain certain parameter values
In case of a power failure