Design of virtual channel queue in an ATM broadband terminal adaptor
H. Jonathan Chao, Donald E. Smith · 1992
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.>