Yves T'Joens Alcatel The Label Distribution Protocol (LDP), as currently defined, makes use of the TCP MD5 Signature option to protect (authentication and integrity) the LDP traffic between two adjacent LSRs. This document specifies extensions to LDP to enable end-to-end authentication between non-adjacent LSR's (ie not directly connected via a TCP connection) that are setting up an LSP. Two mechanisms are defined that also provide integrity protection of the information carried within LDP messages and protect against the malicious replay of LDP messages. Both proposed mechanisms require ordered control LDP and can also be applied to CR-LDP.