A throughput fairness injection protocol for mesh and torus networks

Direct networks suffer significant network unfairness under non-uniform heavy loads; nodes near high traffic areas are hardly able to inject new packets while nodes at low traffic areas may inject packets at high rates. The reported average throughput does not reflect the large differences in node throughput amongst the network. Age-based arbitration has been proposed to achieve latency fairness and in doing so it will indirectly improve throughput fairness as well. However, as throughput fairness is only an issue at heavy loads, we would like a less intrusive method that can be applied to a range of network designs without limiting their routing or arbitration policies. This paper presents a simple injection fairness protocol that guarantees all nodes can inject at a similar rate at high loads regardless of their location. Tests with a variety of non-uniform loads will prove the success of the protocol for a range of network sizes.