An apparatus in a digital network includes the logic for allocating and assigning packet identifiers (PIDs) to digital packets, such as MPEG packets. The logic can reside in a device that transmits a transport stream or a device that controls a transport stream transmitter. In the preferred embodiment, a session number is associated a program and with an output port of a transport stream transmitter; and the session number is unique for that output port. The logic associates a PID from a set of allocated PIDs with the session number. The set of allocated PID values are PMT_PIDs, which are used for identifying the PMT packets, and the set of PMT_PIDs is scalable. In the preferred embodiment, the logic also associates the PMT_PID to the session number using a predetermined scheme. The apparatus also includes logic for assigning a set of PID values to the elementary streams of a program. In the preferred embodiment, number of PIDs assigned to the elementary streams of a program is no more than the number of elementary streams of the program.