University of Tuebingen ZTE Corporation University of Tuebingen This document defines a mechanism for discovering MPLS Network Actions (MNA) capabilities along a Label Switched Path (LSP) using the LSP Ping echo request/reply mechanism defined in RFC 8029. The capabilities include the Readable Label Depth (RLD), the maximum sizes of differently scoped Network Action Sub-stacks (MLD_NAS), and supported network action opcodes. This mechanism allows the ingress Label Edge Router (LER) to discover MNA capabilities of each transit and egress node on the path, enabling correct construction of MPLS label stacks containing MNA network actions.