Design of virtual channel queue in an ATM broadband terminal adaptor

It is desirable to interconnect different computer hosts and local area networks (LANs) through the asynchronous transfer mode (ATM) network via broadband terminal adaptors (BTAs). The BTA must have a sufficiently large buffer, called a virtual channel queue (VCQ), to temporarily store multiple, partially received packets from different virtual channels. The buffer requirement of a shared-memory VCQ is studied for different packet loss probabilities and virtual channel numbers. Two different architectures for implementing the shared-memory VCQ are compared. The second architecture with multiple linked queues in the shared-memory requires less memory and has better scalability to accommodate a large number of virtual channels and is adopted in the analysis. Several possible error conditions, such as shared-memory overflow, the received packet exceeding its maximum length, and the corruption of the pointer in the logical queue, are discussed. Corresponding solutions are proposed in the VCQ designs