Full Protection Made Easy: The DisPath IP Fast Reroute Scheme

A major concern in IP networks is to ensure that any topology changes, whether planned or unplanned, do not disrupt network performance. IP Fast Reroute (IP FRR) is a general approach to address this issue by promptly forwarding an IP packet to a predetermined alternate next-hop as soon as the primary next-hop to the destination becomes unavailable. Among the numerous IP FRR schemes proposed to date, the simplest ones do not guarantee protection against every component failure, while more sophisticated ones tend to be difficult to implement due to various inherent complexities, such as nontrivial modifications of IP packets or high resource requirements. This paper presents a simple and efficient IP FRR scheme called DisPath, which leverages several fundamental properties of minimum-cost node-disjoint paths for determining the alternate next-hop toward a given destination. We show that DisPath ensures full coverage, meaning protection against all single link or node failures, with low computational overhead and without the practical complications encountered by other schemes that offer the same level of protection. Our simulations on several realistic instances reveal that DisPath usually creates shorter (and, at worst, not much longer) alternative paths than existing solutions adopted by the industry. Combined with the aforementioned protection guarantee and simplicity of implementation, these results provide strong evidence that DisPath is a most compelling choice of IP FRR scheme.