If you are building a MAN or WAN utilizing directly attached dark fiber cabling you’ll most certainly want to use SFPs (small form-factor pluggable) or mini-GBICs that have DDI capabilities. With the introduction of 5.x software (I believe it was 5.x software although don’t quote me in the New York Times) for the ERS 8600 switch you can now query the operating parameters of the SFP itself with respect to the optical connection. For those of us that are always worried about dB loss budgets this is an awesome tool to have available and takes a lot of the guess work out of the equation and helps to provide enough information to understand if any signal attenuation is required
Here’s an example of a 1000BaseCWDM (40Km) SFP where the Rx path has been compromised by a squirrel. Yes, true story a squirrel chewed into the cable outside the building and damaged one of the fiber-optic strands in the cable.
ERS-8610:5# show sys pluggable-optical-modules info 1/15 detail
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Pluggable Optical Module Info 1/15 Detail
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Port: 1/15
Type: Gbic1470(40)
DDM Enabled : TRUE
Nortel PEC : AA1419053-E6 CLEI : IPUIAHGWAA
Vendor : NORTEL Vendor PN : AA1419053-E6
Vendor REV : A Vendor SN : LUMNTW7DDT200XXX
Vendor Date : 12/12/07
Wavelength : 1470.00 nm
Digital Diagnostic Interface Supported
DDM Status : Ok
Calibration : External
RX Power Measurement : Average
Auxiliary 1 Monitoring : Not Implemented
Auxiliary 2 Monitoring : Not Implemented
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LOW_ALARM LOW_WARN ACTUAL HIGH_WARN HIGH_ALARM THRESHOLD
THRESHOLD THRESHOLD VALUE THRESHOLD THRESHOLD STATUS
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Temp(C) -24.9960 -24.9960 30.6367 99.9960 99.9960 Normal
Voltage(V) 2.8000 3.1000 3.3080 3.5000 3.8000 Normal
Bias(mA) 4.2500 4.5000 13.2720 100.0120 110.0140 Normal
TxPower(dBm) -6.0 -5.0 -2.0 1.9000 2.9000 Normal
RxPower(dBm) -26.1000 -25.1000 -40.0 -3.0 -2.1000 Normal
Cheers!