c3850-nm-4-1g sfp activity

[gregorydahl]

Using two C3850 48 port, stacked network switches each with a C3850-NM-4-1g module.  Adding SFP modules for fiber single-mode LC connectors.  Ports are configured the same and not shut down, active.  None of switch 1 shows activity using the SFP modules in the C3850-NM-4-1g slots and only ports 2 & 3 are active on the second switch, 1 & 4 are inactive.  

Is there a good method or test to troubleshoot the C3850-NM-4-1g for physical activity? 

[marce1000]

            - Check if the used SFP's are compatible from this list : https://tmgmatrix.cisco.com/?npid=405

 M.

[Leo Laohoo]

Loop the optics (PICTURE).

[Bryson F]

There is a way you can test for physical activity i may get yelled at for saying this but plug in the sfp and if possible turn off the lights in the room and look into it you should see a red light. But also check your pairs on the ends of your fiber and make sure your RX and TX ends are no twisted on one side each half of the pair should be colored ie a red strip and black strip depending on the brand and to also simplify try to use as the same sfp on each end as well. you can buy a fiber cable tester all it does is shoot a beam of light and you go to the other end and look. also for these NM double check your switches that they are on the same version i have had that issue with C9200 10G NM

[Tom Randstrom]

The wavelengths used for optical transmission are not in the visible light spectrum, so you will not know if the laser is on or off.  If you connected a visual fault locator (VFL) to the end of the fiber, the red LED allows you to identify and troubleshoot a fiber. 

[Leo Laohoo]

---

@Bryson F wrote:
There is a way you can test for physical activity i may get yelled at for saying this but plug in the sfp and if possible turn off the lights in the room and look into it you should see a red light.

---

Whao.  Don't do that.  You need a pair of special eyewear to prevent injuring the retina.  

[gregorydahl]

Thank you for the replies, I will be ordering a VFL unit to confirm the module status.