Is setting of setsockopt with IP_MULTICAST_IF or IPV6_MULTICAST_IF valid for a loopback interface. What happens while this option setting fails and we try a sendto() on this loopback interface?
While I tried, setsockopt returns "No such device(19)" and sendto() returns error "Network is unreachable(101)". Are both the calls dependent? What are the constraints for a loopback interface created as an IGMP/MLD interface while setting IP_MULTICAST_IF/IPV6_MULTICAST_IF respectively? What are the possible setsockopt options for a loopback interface?
