ASAP: Preventing Starvation in Backpressure Forwarding

Backpressure forwarding maximizes throughput in dynamic networks. It does not, however, provide any latency guarantees and can result in indefinitely long queuing delays. ASAP (Anti-Starvation with Artificial Packets)solves this starvation problem by: (1)dynamically detecting starvation based on outbound capacity estimates, (2)using virtual packets to convert queuing delay into queue-based gradient increases, and (3)non-linearly add virtual packets after starvation is detected to rapidly respond. ASAP was implemented into a backpressure forwarding system called IRON. Experimental results show that ASAP effectively detects and rapidly addresses starvation when it is occurring, and does no harm when starvation is not occurring.