How does LDP select its router ID in an MPLS network?

LDP selects its router ID based on the highest IP address of an active loopback interface. If multiple loopbacks exist, the one with the numerically highest IP address is chosen. If no loopback interfaces are configured, LDP will then select the highest IP address of an active physical interface. The force keyword is not a standard LDP command for router ID selection and would not change the router ID without impact; it's typically used in other contexts like BGP. While it's good practice for the LDP router ID to match the IGP router ID for consistency and troubleshooting, it's not a strict requirement for LDP operation. An operational physical interface is only chosen if no loopback interfaces are configured.