Layer 1 problem - fiber ethernet won't connect unless held in

Question

I'm attempting to uplink an older D-Link DGS-1224 switch to an HP Procurve 2810 using a 50 meter MM OM3 fiber cable on the bench before running the cable in the plenum for production. Cable is high quality and brand new.

Both transceivers seem to initialize fine in their respective switches but when I connect the LCs on both ends no activity or link is shown.

I found by accident that when I press in the LC connector just a bit further than it normally "clicks" into place on the D-Link the link is up and traffic appears to be moving. As soon as I let go to allow the LC connector to return to its normal resting position the link lights go dark again.

I also tried using an older orange OM1 or OM2 (don't know) cable which is only 8 meters long and got the same result, including link lights when I press it in a bit further.

Has anyone else ever seen something like this before? Is the light not "bright" or powerful enough to be received unless it's closer to the sensor? Should connecting two transceivers and switches made by different vendors be a problem as a general rule? Thanks!

Answer 1

This sounds like an optical problem in the transceiver module - for whatever reason the optics are not lining up correctly when the connector is clicked into place, but are managing to focus when the connector is pushed in further.

I do kinda wonder if everything is clean - filth at a very small scale is the bane of fiber optics in general. If you can't scope every connection before making it it's difficult to know, because (for instance) "I just took off the dust cap, so it must be clean" is not actually true.

In general, there should be no trouble connecting between different makers so long as mode/type/etc. match.