http://www.rfc-editor.org/rfc/rfc6435.txt
RFC 6435: MPLS Transport Profile Lock Instruct and Loopback Functions, S. Boutros, S. Sivabalan, R. Aggarwal, M. Vigoureux, X. Dai2011-11-01T23:00:00-00:00This document updates Sections 7.1.1 and 7.1.2 of RFC 6371. [STANDARDS-TRACK]