Disclosed is a method for receiving a data packet by a receiving apparatus in a multimedia system, the method comprising: receiving the data packet; obtaining, from a payload header of the data packet, a fragment indicator including information about fragmentation of a data unit in a payload of the data packet and a fragment counter indicating a number of at least one payload containing at least one fragment of the data unit succeeding the payload; and identifying that at least one number indicated by the fragment counter is to be reused in a case that the fragment indicator includes a value indicating that the payload contains a fragment of the data unit that is neither a first nor a last fragment, and the fragment counter indicates a number indicating that there is no at least one payload containing the at least one fragment of the data unit succeeding the payload, wherein a total number of fragments of the data unit is larger than a maximum number indicated by the fragment counter.