On the Effectiveness of Proactive Path-Diversity Based Routing for Robustness to Path Failures

Path disuptions (due to congestion, link failures, which may in turn happen during normal operation or caused by malicious activity) are frequent occurrences on the Internet. Thus, several efforts have focused on enhancing robustness from the end-to-end viewpoint by using path diversity. Most of these studies are limited to single– or two-path approaches. This paper is the first to address the question of what degree of path diversity is needed to effectively mitigate the effect path failures. We seek to answer this question through extensive experiments in PlanetLab. To evaluate the effect of path diversity on routing robustness in regards to a wide spectrum of applications, we introduce a new performance metric we named outage duration. Experimental results show that proactively forwarding packets using a high degree of path diversity is more effective in overcoming path failures in comparison with singlepath or two-path approaches. In addition, for applications in which low packet loss probability is as important as uninterrupted connectivity, we suggest a packet forwarding scheme based on link gains and discuss the trade-offs between robustness and packet delivery probability.