Huawei Technologies Huawei Technologies Ionos Networks This document introduces a new optional Cryptographic Authentication TLV that LDP can use to secure its Hello messages. It secures the Hello messages against spoofing attacks and some well-known attacks against the IP header. This document describes a mechanism to secure the LDP Hello messages using Hashed Message Authentication Code (HMAC) with the National Institute of Standards and Technology (NIST) Secure Hash Standard family of algorithms.