editor This Internet draft discusses many of the issues associated with user plane OAM for MPLS. The goal being to provide tools to perform 'in service' maintenance of LSPs. Included in this discussion is some of the implications of MPLS architecture on the ability to support fault, diagnostic and performance management OAM applications, potential solutions for distinguishing user plane OAM, and a summary of what the authors believe can be achieved in addressing all aspects of the MPLS architecture.