Roughly described, incoming data packets are delivered by the NIC directly to at least two user level endpoints. In an aspect, only filters that cannot be ambiguous are created in the NIC. In another aspect, the NIC maintains a filter table supporting direct delivery of incoming unicast and multicast data packets to one user level endpoint. Additional requests to join the same multicast group cause replacement of the NIC filter with one in the kernel. In another aspect, a NIC has limited capacity to maintain multicast group memberships. In response to a new multicast filter request, the kernel establishes it in the NIC only if the NIC still has sufficient capacity; otherwise it is established in the kernel.