Implementing a flexible synchronous network

The SYNET project, undertaken by Deutsche Telekom to modernize its transmission network, is discussed. The SYNET technology is based on the synchronous digital hierarchy (SDH), which uses synchronous transport modules of 155 Mbit/s (STM-1). The latter include a maximum usable bit rate of about 50 Mbit/s as well as a variety of additional information intended for network management. Since the transmission network is divided into several network levels characterized by different traffic loads and structures, a range of synchronous components geared to the requirements of the different network levels have been developed. The major differences between the trunk network and the local networks are described. The implementation of SYNET is reviewed