See second bullet on page 19-307, Chapter 19, "Configuring ERSPAN: Guidelines and Limitations". - "ERSPAN is not supported for management ports."   As to why it is not supported? Well, that is a question for the NX-OS developers...but as appears to b...

Thanks. How do we artificially configure a lower threshold to force the generation of an 'entSensorThresholdNotification' SNMP trap?