Discussion on the combination of Loop-Free Alternates and Maximally Redundant Trees for IP networks Fast Reroute

Abstract

IP Fast Reroute (IP FRR) is the IETF standard for providing fast reaction to failures in IP and MPLS/LDP networks. In the past decade, several IP FRR proposals have been proposed, and among them Loop-Free Alternates (LFA) is the simplest, but it cannot achieve 100% single failure coverage. In contrast, Maximally Redundant Trees (MRT) can provide 100% single failure coverage and seems a promising scheme. However, MRT has some drawbacks as it can lead to long backup detours and heavy network congestion. In this paper we combine MRT with LFA to merge their advantages and improve the quality of protection. Observations of performance evaluation suggest that with almost same time and resource consumption as MRT, our mechanism can greatly enhance the quality of protection in terms of backup path length and maximum link utilization.