Fiber connection between two switches will not stay up.

[zackburf]

Good morning. I manage a network with about 90 switches all connected via fiber.  I have one switch that is giving me issues.  It will stay up for about an hour then go down.  We have tried replacing all the hardware on both sides and there is no difference the only thing that seems to help is when we clean the end, it will work for a little bit then drop again.  Could there be some oil or dust that lets it connect then interferes with the traffic and kills the connection?   Any ideas?

[SimonV]

What length and type of fibre are you running and which SFPs are you using? Are your patch cords the same spec as the fibre runs?

[zackburf]

Its about 1 200 meter pull using 1.25mm fiber.  And yes they are the same. We have used this exact setup at all of our 80 other switches and have not had any issues.

We moved it to some transceivers that run at 100 megs which is what the old equipment ran at and it seems to be fine now....even though its slow again.
So why does it stay up at 100 megs but drop AFTER a brief up period at 1 gig?

update:  The 100 meg transceivers just dropped too.

[icecream-guy]

What does the OTDR say when you test the fiber cable?

there are also come cisco comannds ( if these are Cisco ) to identify power on the transceivers.
I forge the commands tho.

[SimonV]

Cisco Digital Optical Monitoring: https://supportforums.cisco.com/t5/network-infrastructure-documents/digital-optical-monitoring-dom/ta-p/3120342

Have you had the cables tested and certified?

How about this test scenario: temporarily install two new switches, with new SFP's, on that fibre run. If these go down too, it's a cabling issue. If not, focus on the hardware.

[zackburf]

Just wanted to update everyone. We purchased some Fiber optice microscopes and it was pretty clear the issue was the ends.  We put on new Unicam ends and everything has been great the last couple of days.

We are looking at buying some actually testing equipment. Does anyone have any recommendations on affordable OTDR's or OLTS sets?

Thanks again.

[icecream-guy]

Fluke usually has some pretty good stuff, but pricey.