Routing with joker links for maximized robustness
Hung Quoc Vo, Olav Lysne, Amund Kvalbein · 2013
IP Fast Reroute methods that are currently deployed in link-state routing protocols with hop-by-hop forwarding, such as Equal-Cost Multi-Path (ECMP) and Loop Free Alternates (LFA), share two common important properties. First, they never form forwarding loops, even when there are multiple independent failures in the network. Second, they do not introduce non-standard packet marking to convey information associated with network faults. However, these Fast Reroute methods give very poor fault coverage; in most cases below 50% of links are protected when using typical link weight settings. This paper presents a new routing method that combines the concept of permutation routings with joker links, called joker-capable permutation routings. Our method results in a routing strategy that shares with ECMP and LFA the stated important properties. Through experiments we show that we protect more than 95% of links for all tested ISP networks. Measurements also show that our method is computationally feasible and performs traffic distribution efficiently under high fluctuations of traffic demands.