The purpose of the ATM adaptation layer (AAL) is to receive the data from the various sources or applications and convert or adapt it to 48-byte segments that will fit into the payload of an ATM cell.

• ATM适应层（AAL）的作用就是从不同的来源或者应用接收数据并转换或改写成能放入一个ATM信元的有效载荷的长度为48字节的段。