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I have a Cisco SFP module that I might need in a few weeks, I don't want to pull it out but I wanted to know if I shutdown the port does it turn off the SFP module, I don't want to leave the laser on if it doesn't need to be powered on.

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"DO NOT LOOK INTO LASER WITH REMAINING GOOD EYE." –  Evan Anderson Feb 2 '11 at 3:08

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up vote 2 down vote accepted

I can't find anything in the documentation indicating any way of ensuring the laser is off. The only things I find are a bunch of warnings which seem to indicate that once it's plugged in the laser may be on. If it's only a few weeks I would just make sure the dust cap is installed and don't worry about it as these devices are designed to run for years. Otherwise pull the SFP. Cisco recommends limited plugging and unplugging of SFPs though. I'm speculating but this seems to indicate that the laser is always on when the SFP is installed and repeated removals might shorten the life of the SFP.

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+1 dust cap. Someone told me that SFPs don't generally have lasers in them any more, they use LEDs of some kind. In any case, the warning about not excessively plugging and unplugging SFPs is because the connector assemblys on the back are not very robust and they will break if exercised too much. –  David Mackintosh Feb 2 '11 at 14:57
    
@David Mackintosh: LEDs are commonly used to drive multi-mode fiber, but lasers are still used for most single-mode fibers. –  Evan Anderson Feb 4 '11 at 11:43
    
@Evan: Ah, that would explain it, I'm mostly multi-mode here. –  David Mackintosh Feb 4 '11 at 15:35

I believe that Admin down cuts power to the module.

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