payload type identifier (ATM) (PTI)
- InATM cells, the Packet Type Identifier (PTI) is a 3-bit long data field. The PTI field indicates whether the cell contains user or management data and whether overload situations have occurred on the cell's path. The first bit indicates which type of AAL, ATM Adaption Layer (AAL), was used to format the data in the payload, the second bit is used for congestion control, Explicit Forward Congestion Indication( EFCI), and informs the application of possible delays or congestion, and the third bit indicates whether the cell contains Operation, Administration, and Maintenance ( OAM) data.
- In X.25, the Packet Type Identifier (PTI) is an 8-bit long data field that defines the particular packet type. The information in this field is used to distinguish individual data packets.