Impact of per-VC and single FIFO queuing on ABR congestion control

Queuing disciplines and their impact on congestion of Available Bit Rate (ABR) service in Asynchronous Transfer Mode (ATM) networks are investigated. In particular, two queuing disciplines, namely, First-In-First-Out (FIFO) and per-VC (virtual connection) queuing, are examined. Performance in terms of fairness, throughput, cell loss rate, buffer size and network utilization are benchmarked via extensive simulations. Implementation complexity analysis and tradeoffs associated with each queuing implementation are addressed. In contrary to the common belief, our investigation demonstrates that per-VC queuing which is costlier and more complex does not necessarily provide any significant improvement over the simple FIFO queuing. These significant results will be of great interest and industrial value to the ATM Forum and vendors. Congestion control algorithms should be designed in such a way that they function well even in the presence of simple queuing disciplines.