Improving network performance with a polarization-aware routing approach

Abstract: Traffic polarization in networks refers to the phenomenon where traffic tends to concentrate along specific routes or edges when doing multipath routing, leading to imbalanced flow patterns. This spatial distribution of traffic can result in congested and overburdened links, while other routes remain underutilized. Such imbalanced traffic distribution can lead to network bottlenecks, reduced throughput, and compromised Quality of Service for critical applications. These issues emphasize the urgent necessity to address traffic polarization and its detrimental impact on network efficiency and resilience. In this master thesis, we introduce a novel approach to tackle the problem of hash polarization and evaluate the performance of our implementation. Perhaps influenced by the RFC 2992 document, previous works always use the whole value of the hash result to do the multipath routing decisions, and therefore try to mitigate the polarization problem by developing more functions or reusing them. However, we investigate if the polarizion issue can be solved by utilizing different parts of the hash result. In this case, the most critical problem would be how to choose the bits of the hash result for the multipath routing decisions. Unfortunately, during the experiment, we discovered that the optimal performance design is influenced by many factors in the network topology and traffic demand pattern, making it difficult to summarize a universal law. Nevertheless, our research has proposed a mechanism called “bit-awareness”, which can significantly alleviate the problem of selecting overlapping bits, and hence addresses the polarization issue.