A CRMA based Gbit/s LAN-ATM based broadband ISDN gateway

The design issues for a high-throughput gateway between a gigabit/second LAN based on the CRMA access protocol and a broadband ISDN (B-ISDN) based on asynchronous transfer mode (ATM) are presented. An alternative to the ATM adaptation layer proposed by the CCITT that allows fast HW-based processing of frames inside the gateway is introduced. The hardware architecture of the gateway is described with particular reference to the mechanisms used to implement the SAR protocol. A comprehensive simulation study on the gateway buffer size requirements is presented, assuming a realistic CRMA network scenario. Different situations are considered in evaluating the buffer occupancy, and some criteria for the buffer dimensioning are proposed