A shared I/O subsystem having a forwarding table and a plurality of I/O interfaces. The forwarding table has a plurality of entries that correspond to each of the I/O interfaces. The shared I/O subsystem receives a data packet from one of the I/O interfaces where the data packet includes a plurality of address bits, applies the address bits of the data packet to the forwarding table, and discards the data packet if applying the address bits of the data packet to the forwarding table fails to result in identification of a valid destination.