Recently, traffic engineering mechanisms have been developed that guarantee that a network (cloud provider WAN, or ISP) does not experience congestion under failures. In this paper, we show that the state-of-the-art congestion-free mechanism achieves performance far short of the network's intrinsic capability. We propose PCF, a set of novel congestion-free mechanisms to bridge this gap. PCF achieves these goals by better modeling network structure, and by carefully enhancing the flexibility of network response while ensuring that the performance under failures can be tractably modeled. All of PCF's schemes involve relatively light-weight operations on failures, and many of them can be realized using a local proportional routing scheme.
All variants of PCF significantly outperform FFC, the state-of-the-art scheme from Microsoft.
A fully distributed variant(PCF-LS) of PCF improves over FFC by 25% on average, and performs 2.6x better in the best case.
Another variant(PCF-CLS) improves over FFC by 50% on average, and matches the optimal for most cases.