Latency-Aware Forwarding for IRON: Latency Support for Back-Pressure Forwarding

We introduce Latency-Aware Forwarding for IRON, the first comprehensive implementation of a networking solution based on Back-Pressure Forwarding (BPF) with broad support for latency-sensitive traffic. IRON, “Intrinsically Resilient Overlay Network”, has been developed to provide the proven properties of BPF in robustness and throughout optimality while offering higher quality-of-service for latency-constrained traffic. Latency-Aware Forwarding adds support for latency-sensitive traffic while maintaining the throughput optimality for latency-insensitive flows. Latency-Aware Forwarding combines a number of advances to a) forward latency-constrained packets along delay-appropriate paths b) reduce the processing time of these packets at each hop. We detail various techniques developed in support of the two goals above and demonstrate that our approach maintains throughput optimality under the tested conditions. We compare Latency-Aware Forwarding to traditional and workconserving BPF and share results from IRON over a physical network, where we show a 233% increase in goodput in delivery of delay-constrained traffic.