This topic describes the specifications for the 28-Gbps quad small form-factor pluggable (QSFP28) optical transceivers used in the QFX10000 line of switches. The optical transceivers installed in QFX Series devices support digital optical monitoring (DOM) and digital diagnostic monitoring (DDM). DDM not only performs optical monitoring but also electrical monitoring, such as power supply voltage. You can view the diagnostic details for these transceivers from the CLI by issuing the operational mode CLI command show interfaces diagnostics optics. The command does not give any output for copper transceivers or transceivers not purchased from Juniper Networks. In the newer standards, optical modulation amplitude (OMA) is used to measure the absolute receiver sensitivity. Older or slower transceivers use average sensitivity as the measure of receiver sensitivity.