Because AAL5 minimizes overhead and offers better error detection, it is preferred for efficient transport of TCP/IP and frame relay traffic.
AAL5 makes use of variable length protocol data units (PDUs).
This would be too large to fit in one 48-byte ATM cell payload, so the segmentation and reassembly (SAR) sublayer of AAL5 breaks down the PDU into 48-byte chunks for transport over the network.
The switches route and monitor individual cells, but without decoding, AAL5 cannot analyze length or CRC errors.
An optical splitter inserted between the ATM switch and router allows for the monitoring of the physical layer as well as AAL5 traffic.
Further, the AAL5 ATM adaptation layer was used to convert TCP packets into ATM cells.
With AAL5, packets will be forwarded only when a marked final cell is received.
Since successful transmission of the last cell is important to the AAL5 algorithm for delineating packets, the CLP bit is not set in the last cell.