Patent ID: 6882650

Claim:
A dual AAL1 (ATM Adaptation Layer Type 1) device with a dual configuration consisting of an act system and a standby system to convert the STM (Synchronous Transfer Mode) data into ATM (Asynchronous Transfer Mode) cells in said act system and said standby system respectively comprising, for said act system and said standby system respectively, means for extracting the SC (Sequence Count) information of said ATM cell where a particular time slot of said STM data is allocated and the allocation position information for the SAR-PDU (Segmentation And Re-assembly-Protocol Data Unit) payload when this means belong to said act system, and means for calculating the SC of said ATM cell where a particular time slot of said STM data in the next frame is allocated and the allocation position for said SAR-PDU payload based on the SC information and the allocation position information extracted by said act system when this means belongs to said standby system.