Use the following command to get optical signal strength. Note: not all types of links have such channel monitor values. The AOC and DAC cables do not have such values.

Generally, optical power should be greater than -10dBm.

• Example:

admin@sonic:~$ sudo sfputil --dom -p Ethernet12
Ethernet12: SFP detected

        Connector : Unknown
        EncodingCodes : Unspecified
        ExtIdentOfTypeOfTransceiver : GBIC def not specified
        LengthOM3(UnitsOf10m) : 144
        RateIdentifier : Unspecified
        ReceivedPowerMeasurementType : Avg power
        TransceiverCodes :
                10GEthernetComplianceCode : 10G Base-SR
                InfinibandComplianceCode : 1X Copper Passive
        TypeOfTransceiver : QSFP
        VendorDataCode(YYYY-MM-DD Lot) : 2013-11-29 
        VendorName : MOLEX
        VendorOUI : MOL
        VendorPN : 1064141400
        VendorRev : E th
        VendorSN : G13474P0120
        ChannelMonitorValues :
                RX1Power : -5.7398dBm
                RX2Power : -4.6055dBm
                RX3Power : -5.0252dBm
                RX4Power : -12.5414dBm
                TX1Bias : 19.1600mA
                TX2Bias : 19.1600mA
                TX3Bias : 19.1600mA
                TX4Bias : 19.1600mA
        ChannelStatus :
                Rx1LOS : Off
                Rx2LOS : Off
                Rx3LOS : Off
                Rx4LOS : Off
                Tx1Fault : Off
                Tx1LOS : Off
                Tx2Fault : Off
                Tx2LOS : Off
                Tx3Fault : Off
                Tx3LOS : Off
                Tx4Fault : Off
                Tx4LOS : Off
        ModuleMonitorValues :
                Temperature : 23.7500C
                Vcc : 3.2805Volts
        StatusIndicators :
                DataNotReady : Off