Current signalling used by Multi-Protocol Label Switching Traffic Engineering (MPLS TE) does not provide support for unnumbered links. This document defines procedures and extensions to Constraint-Routing Label Distribution Protocol (CR-LDP)@ one of the MPLS TE signalling protocols that are needed in order to support unnumbered links.
RFC 3480-2003 history
2003RFC 3480-2003 Signalling Unnumbered Links in CR-LDP (Constraint-Routing Label Distribution Protocol)