Abstract: This paper presents an End-to-End (E2E) Operations, Administration, and Maintenance (OAM) architecture for Telco networks including a Sub-wavelength domain. It addresses two main issues: compatibility between MPLS networks and different Sub-wavelength technologies, and scalability of the OAM flows across the whole network. This is the first study on a methodology to scale the number of OAM flows in an E2E scenario combing both subwavelength (OPST technology) and MPLS switching domains. Finally, the inter-carrier issue in E2E OAM is also explored.