Is it possible to have multicast traffic on wireless APs sent to a certain stations and have no affe

Is it possible to have multicast traffic on wireless APs sent to a certain stations and have no affect on the rest of the associated stations?

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Multicast can be used in a wireless network to reduce the bandwidth consumed by applications that wish to transmit the same data to many recipients. When a station has a multicast message to send, the original message is sent as a unicast frame to the AP. The AP acknowledges the unicast frame before retransmitting that message as a multicast frame to a group address. Every station in a multicast group listens for multicast frames, but they do not acknowledge multicast frames. 802.11 multicast is thus a best effort delivery service.

Multicast and broadcast are different. Broadcast frames are directed to ALL stations by filling the group address field with all ones (FF:FF:FF:FF:FF:FF), whereas multicast frames are directed to an address assigned to a given multicast group. Broadcast frames are thus intended to affect every station associated the AP, while multicast frames are intended to affect only those stations participating in a given multicast group.

However, keep in mind that 802.11 channels are shared media. All transmissions -- whether broadcast, multicast, or unicast -- consume bandwidth and therefore reduce the resources available to other stations competing for that same channel.

This was first published in February 2006

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