A type of
loopback (PLB) performed by a
CSU/
DSU to test
data integrity. Payload can be a regenerated loop in a CSU or
IP packet contents.
Specifically, it is a portion of a cell, frame, or packet that contains upper-layer information (data). In ATM, a payload type identifier (PTI) is a 3-bit descriptor in the cell header indicating the payload type. Types include user and management cells.