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ka9q / ka9q-radio

Multichannel SDR based on fast convolution and IP multicasting
GNU General Public License v3.0
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Joining multicast groups on multiple interfaces? #17

Closed ka9q closed 2 years ago

ka9q commented 2 years ago

Question: on both Linux and MacOS/UNIX, multicast groups are joined on a per-interface basis. For those programs within ka9q-radio that transmit, it's important to limit them to particular interfaces (usually Ethernet) to avoid flooding a WiFi network. But what about receiving? Should the monitor program, which only receives, automatically join a multicast group on all available interfaces?

ka9q commented 2 years ago

One drawback would be a computer on both Ethernet and Wifi, with a bridge between the two. Joining a multicast group on both interfaces would draw traffic to both, unnecessarily loading the WiFi when the Ethernet alone would be sufficient. But this means having to specify the interface along with the multicast DNS name (or IP address) when it's not the default.