This ETR provides a current overview of work recognized as already done or in progress within the ETSI TC TM on issues covering the Synchronous Digital Hierarchy (SDH) and also it searches for compatibility with other future, current and past technologies and hierarchies. The ETR shall in future describe all SDH aspects to be standardized and their relationship to appropriate work items (WIs), and already published standards (ETSs) and reports (ETRs). Also work done in other Technical Commitees with aspects of SDH or impact on SDH shall be considered and harmonized. The TC recognized to be standardizing Architecture, Protocols, and Interfaces being on the boundary with SDH or using SDH networks are: NA, BTC, and TE. NOTE: The TC list is exhaustive and will be updated with any new TC recognized.