This solution provides SDH and SONET functionality at 40G with generation and analysis of framed signals with errors, alarms, overhead and test payload. This includes also unframed signal generation and analysis at 40G line rate. The interface is optical at 1550nm. The ONT-40/43G solution supports testing and verification for new high-speed network elements up to 40 Gb/s. It allows the evaluation of the physical layer, at bit rates of 40G with unframed signal and framed signals for SDH/SONET. Function and conformance testing are also provided for the transport layer.