and may follow a proprietary or standardized zigbee application profile such as e g home automation ha commercial building automation cba or smart energy zse profile the zigbee device object zdo manages the zigbee device and is u2014 among others u2014 responsible for the network selection for the initialisation of the zigbee layers with the exception of the application objects ao 1 ao 240 the definition of the actual function of the zigbee device zed zr or zc the discovery of other devices in the network and the initiation of sending binding requests a security service provider sec is responsible for exchanging and maintaining security credentials as well as security operation such as encryption and authentication referring to fig2 it will be roughly explained how an unconnected zigbee device may join an existing zigbee network according to the current zigbee standard thereby the still unconnected seeking device intending to join the network will scan for potential parent devices by broadcasting a request signal listening for beacon signals from devices within range and determining the link cost for each responding device the scan may be performed by a listening unit lu of the medium access control layer mac see fig1 and a link cost calculation unit lc may calculate the link costs according to equation 1 above the data from the beacon signal of each discovered potential parent device.