The OTN brings the potential for a simplified transparent transport network that can ultimately replace SONET/SDH at Layer 1. In order to do this, however, the OTN must be capable of carrying a number of important legacy, including GE and SONET/SDH, and emerging client signals with sub-ODU1 rates, including SAN and native video signals. This white paper summarizes the different approaches that have been considered for transporting sub-ODU1 client signals. While one approach, the ODU0, has been standardized by the ITU-T, it will be many years before ODU0 support is available in the OTN. The need exists for alternative methods that can be deployed in the meantime, and also to support important long term applications. This white paper describes the alternatives for sub-ODU1 rate client signal transport, and the applications for each.