11.2 How to Use Filters

Whenever the application wishes to use a multicast IP address, for either sending or receiving, a filter is needed. The application can establish this through setting the IP_ADD_MEMBERSHIP option for the required socket accompanied by the multicast address that the application wants to use. If subsequently the host wants to stop receiving the multicast stream, set the IP_DROP_MEMBERSHIP option for the required socket accompanied with the multicast address.

Adding or removing a multicast address filter causes the WINC chip firmware to add/remove both MAC layer filter and IP layer filter in order to pass or prevent messages from reaching to the host.