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Multicast to certain interfaces only

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  • Multicast to certain interfaces only

    There really needs to be a way of specifying what interfaces a multicast message will be sent over.

    My bridge script has certain messages that are directed inwards, to SNAPConnect via a serial port, and other messages that are directed outwards, over the air; in no case does a message ever need to go both ways. I can keep the inbound messages mostly restricted to the serial port (by making them unicasts, with the route timeout set to 0), but the outbound messages are all multicasts, and there's no current way to keep them from also being transmitted over the serial port. One of our customers has reached 1000 nodes in their network, and these useless misdirected messages are eating up all of the serial port bandwidth, causing many of the legitimate inbound messages to be lost.

    Perhaps the high byte of the TTL parameter could be used for per-interface flags - 0x0100=dontUseRadio, 0x0200=dontUsePacketSerial, etc. Alternatively, there could be a NV param for each interface, specifying which multicast groups are to be sent over that interface. The existing ID 78 is along the right lines, but only affects forwarding, not the original transmission. (I'd personally prefer the first solution, as I'm already using all 16 multicast groups, to partition network traffic.)