A. Paraschiv Nortel Networks This document describes the encoding and procedures for three new Label Distribution Protocol (LDP) messages: Query Message, Query- Reply Message and Partial Query-Reply Message. A Label Edge Router (LER) sends a Query message when it needs to find out information about an established Label Switched Path (LSP). The Query message can be used for LDP LSPs as well as for Constraint-Based Label Switched Paths (CR-LSPs). The queried data is encoded into the Query-Reply messages.