... swaps the target and sender address pairs in the ARP datagram (both HA and PA), inserts its own MAC address into the relevant field, changes the operation code to 2 (ARP reply), and sends it back ... opcode of 3 (RARP request), and identifies itself as both the sender and the target by placing its own physical address in both the sender hardware address field and the target hardware address ... combination of a source IP address and a non- zero flow label. A flow label is assigned to a flow by the flow’s source node. Flow labels are chosen (pseudo-) randomly and uniformly from the range...