Segmentation and Reassembly

Segmentation and Reassembly is the process used to fragment and reassemble variable length packets into fixed length cells so as to allow them to be transported across Asynchronous Transfer Mode networks or other cell based infrastructures. Since ATM's payload is only 48 bytes, nearly every packet from any other protocol has to be processed in this way. Thus, it is an essential process for any ATM node. It is usually handled by a dedicated chip, called the SAR.