> It sounds like I need to have a look at how multicast filtering works with
> supported PCI nic cards and apply that to nusb/ether.
You don't have to do full filtering - it's enough to enable the adapter
to receive all multicast messages and the kernel driver will filter out
the uninteresting ones. Some of the PC ether drivers work this way.
There's already a patch in /n/sources/patch/usbether-rpi which enables
multicast for usb/ether. I had to write this in order to make ipv6 work
on the raspberry pi.