Recovery from Shared Risk Link Group Failures Using IP Fast Reroute

Failure recovery in IP networks is critical to high-quality service provisioning. In IP over wavelength division multiplexing (WDM) networks, a fiber carries multiple IP logical links. When a fiber fails, all the logical links it carries are disconnected simultaneously. This is called a shared risk link group (SRLG) failure. Recovery from SRLG failures using route recalculation could lead to long service disruption. In this paper, we present a scheme called multi-section shortest path first (MSSPF) that achieves ultra fast recovery from SRLG failures. MSSPF performs all the recovery related calculations in advance. On the detection of an SRLG failure, the affected IP packets are detoured to their destinations through pre-calculated paths to avoid failed links. We prove that MSSPF guarantees 100% recovery from SRLG failures and causes no permanent loops. In particular, the scheme has low complexity and can be implemented in today´s networks running link-state routing protocols, e.g., open shortest path first (OSPF). The performance of our scheme is validated with a variety of practical and randomly generated topologies.