LDP Extension for Inter-Area Label Switched Paths (LSPs)
RFC 5283

Received changes through RFC Editor sync (changed abstract to 'To facilitate the establishment of Label Switched Paths (LSPs) that would span multiple IGP areas in a given Autonomous System (AS), this document describes a new optional Longest-Match Label Mapping Procedure for the Label Distribution Protocol (LDP).

This procedure allows the use of a label if the Forwarding Equivalence Class (FEC) Element matches an entry in the Routing Information Base (RIB). Matching is defined by an IP longest-match search and does not mandate an exact match. [STANDARDS-TRACK]')