A PE router receives an LDP label mapping for 10.10.10.0/24 but its FIB has no route to that prefix. What is the observed behavior on the router?

LDP (Label Distribution Protocol) requires a corresponding entry in the IP routing table (FIB - Forwarding Information Base) for a prefix before it can install a label into the LFIB (Label Forwarding Information Base). If a PE router receives an LDP label mapping for a prefix (e.g., 10.10.10.0/24) but lacks a route to that prefix in its FIB, it will not install an LFIB entry. Instead, it will retain the received label mapping in its LDP database, awaiting the appearance of a matching FIB route. Once a route is installed in the FIB, the router can then install the corresponding label into the LFIB. The router does not immediately forward labeled packets without a FIB entry, convert the mapping to a static route, or automatically withdraw the label; it simply waits for route convergence.