350-060 Question #73: Real Exam Question with Answer & Explanation

Refer to the exhibit. Refer to the topology diagram for a service provider that is offering L3VPN services. PE1, PE2, PE3, and PE4 are provider edge routers that are connected to the core P routers. They are learning VPNv4 prefixes from different sites. The MPLS core is LDP-enabled and is running OSPF as an IGP. One of the P routers that is connected to PE1 and PE2 has an LDP defect in which the LDP session periodically resets and then manages to recover on its own. While the LDP session resets, an outage is observed on L3VPN traffic that needs LDP to maintain a label-switched path. While a software fix has been identified and is in the works, which MPLS or IGP feature will avoid this problem?