Loop-Free Alternates and Not-Via Addresses: A Proper Combination for IP Fast Reroute?

Date Added: Nov 2009
Format: PDF

The IETF currently discusses Fast Re-Route mechanisms for IP networks (IP FRR). IP FRR accelerates the recovery in case of network element failures and avoids micro-loops during reconvergence. Several mechanisms are proposed. Loop-Free Alternates (LFAs) are simple but cannot cover all single link and node failures. Not-via addresses can protect against these failures but are more complex, in particular, they use tunneling techniques to deviate backup traffic. In the IETF it has been proposed to combine both mechanisms to merge their advantages: simplicity and full failure coverage. This paper analyzes LFAs and classifies them according to their abilities.