In802.11WLANs, the clients can operate in a power-save mode to save energy. They are then excluded from active communication. Multicast and broadcast messages directed to them are buffered in the radio access point.
The access point informs the client during a beacon period with a Delivery Traffic Indication Message (DTIM) about the cached broadcast and multicast messages and that the access point transmits them after counting down a counter. The counter reading is transmitted in the Traffic Indication Message( TIM), which corresponds to the beacon interval, whereas the DTIM interval is a multiple of the TIM interval. The DTIM interval at which the access point broadcasts the DTIM message can be configured in the access point. The power save mode can be set by the user on the client.