For an accelerated socket, Onload will usually behave as if IP_MULTICAST_ALL=0. However:
- If two multicast sockets are bound to INADDR_ANY:<same_port> in different stacks, then Onload does behave as if IP_MULTICAST_ALL=0. But if the sockets are in one stack, then they both receive all packets, as if IP_MULTICAST_ALL=1.
The behavior is even more complex if the sockets join the same address on different VLANs.
- There is always the potential for messages to arrive at the host - perhaps from an unsupported interface or via the loopback interface - which will also be delivered to the socket under normal UDP port matching rules so the socket could receive traffic for groups not explicitly joined on this socket.