Efficient implementation of the SAR sublayer and the ATM layer in high speed broadband ISDN data terminal adapters

An efficient terminal adapter for the broadband integrated services digital network (B-ISDN) is presented. The adapter performs in the asynchronous transfer mode (ATM) environment. It is optimized for efficient transfer of bulk data, while maintaining simplicity and transparency. The adapter has been designed in comformity with evolving standards. Its flexible design supports future extensions and protocol alternations. The architecture of the adapter incorporates into a single component the ATM layer and the segmentation and reassembly (SAR) sublayer functions for connection-oriented data transfer. The adapter can handle data at full rate (155 Mb/s on the ATM I/F), while introducing constant protocol overhead delay. The adapter efficiently utilizes the available buffer irrespective of the size of the transferred data unit