The deterministic packet marking (DPM) method is based on marking packets with the partial address information of ingress interface only. The attack victim is able to recover the complete address(es) information after receiving several packets from a particular attacking host or hosts. The full path is not really essential for the traceback since it can be different for different packets for different reasons. In order to deal with fragmentation, it is required that the ID field (as well as some other fields) of all the fragments in a given series is the same. DPM randomly selects the marks from the pool, which is created at startup. The mark completely occupies the ID field in the IP packet header, as well as Reserved Flag. Since every single packet passing through the DPM-enabled interface is marked, the ID field of all the fragments of a series are ensured to be the same. By allowing DPM to suspend randomness in selecting the marks for the fragments of a series, all fragments are ensured to have the same ID. This ID would be different from the one originally set by the origin of the packet, but this would not make a difference for the reassembly process.