Hello albertsilva, these concepts should help you
PLR, Local repair point is the main node of the protection LSP, that is, the location where the failure occurs. When protection occurs, the protection label is pressed at this point and the normal label is encapsulated in it.
MP, Melting point is the queue node of the LSP protection. When protection occurs, the protection label is displayed at this point, and the protection label is normally forwarded according to the original label.