Fibre Optic Help

[Shadow_Walker]

Strange issue and mind has gone blank. We have an OM4 run of fibre between our core and an edge switch and for some reason yesterday it stopped working. I have got lights inside the fibre patch panel and when i plug a patch cable in it can be seen in the patch cable. When I plug it into the Aruba module in the switch i get no uplink lights.

 

I have removed the Aruba Module and plugged it back in and get green light when it is plugged back in but when i plug the fibre in I get nothing.

 

Any ideas?

[Davit2005]

Have you tried different patch cables either end, the green blink is what you normally get when you plug an SFP in as an acknowlegment.

 

Don't be tempted to look down the patch cable with your naked eye but I normally use a phone or something similar to check for light as a very basic test.

[Shadow_Walker]

Yes different patch cables on both ends but still no difference. Just ordered some more just in case. Anything else to look for?

[Chaniel]

Have you swapped the SFP module? Could be that has gone faulty.

 

What do the logs say on the switch?

[PotNoodleTech]

If you turn the lights off and use a piece of white paper you can check if there is light coming out of the SFP module itself. If not then changing cables is not going to make a difference. Do this both ends then work your way down, plug a patch cable in and is there light coming out of the patch cable, plug the patch cable in fully and is there light coming out of the fibre patch pannel. Do this both directions.

[Shadow_Walker]

Checked the lights on both sides and all is working. Switch A > Patch lead (red light) > Patch panel (red light on patch lead plugged into red light on patch panel) > Patch Panel B (Red light showing) > Patch Cable (Red light coming through) > Module light on (plugged patch cable into corresponding light)

 

Not sure what else it could be now.

[bald_pig]

Checked the lights on both sides and all is working. Switch A > Patch lead (red light) > Patch panel (red light on patch lead plugged into red light on patch panel) > Patch Panel B (Red light showing) > Patch Cable (Red light coming through) > Module light on (plugged patch cable into corresponding light)

 

Not sure what else it could be now.

 

Did you check both directions?

 

And have you made sure that the port is enabled on the switch? could be disable in the ui.

[Shadow_Walker]

Did you check both directions?

 

And have you made sure that the port is enabled on the switch? could be disable in the ui.

 

If the light is showing one way surely it will be the same the other way, or are you saying start at switch B and go back to Switch A?

[Shadow_Walker]

And have you made sure that the port is enabled on the switch? could be disable in the ui.

 

Plugged console cable in and the port is active and has detected the SFP Module.

[bald_pig]

If the light is showing one way surely it will be the same the other way, or are you saying start at switch B and go back to Switch A?

 

Not if the fault lies with the SFP module though!

[Shadow_Walker]

Not if the fault lies with the SFP module though!

 

Not quite sure what you mean now then, if the SFP module on both sides has a red light then are they working?

[Davit2005]

What connectors are you using, LC? If you are using ST or SC are they around the right way. Generally you will have 2 cores one rx and one tx.

[Shadow_Walker]

What connectors are you using, LC? If you are using ST or SC are they around the right way. Generally you will have 2 cores one rx and one tx.

Yep have done the switch of A and B

 

These are the ones

 

https://www.comms-express.com/products/lc-lc-connector-multimode-duplex-fibre-patch-leads/?0.5~Metre?50/125~(OM4)

[Chris_Cook]

I'd swap the modules out, one end at a time.

 

We've had several modules fail on the receive side, so there is no easy way to see if its working or not as you would still get the red laser coming out.

[Shadow_Walker]

I have new cables arriving tomorrow and grabbing some spares from one of our other schools. Just to rule it it out do you think the fibre cable itself is fine then

[Shadow_Walker]

Still got this issue, anyone got any ideas?

[Chris_Cook]

So to recap -

 

* light can get from one end of the fibre cable to the other, on both sides.

* light can get from one end of the patch cables to the other, on both sides.

* reversing one of the patch cables didn't fix it

* new sfp modules didn't fix it

* reversing the patch cables back the way they were after replacing the sfp modules didn't fix it.

 

Do you have anything like VLANs or LACP trunked links in use? If these aren't configured correctly they can cause links to not come up.

 

Is there another pair on the fibre cable you can try?

 

Can you swap each bit out on another fibre link?

 

If you have the right patch cables, I'd try connecting a switch locally using the fibre.

 

If none of that works, I'd get a fibre installer to come in and verify the link. It could be damaged in a way that doesn't transit enough light to get a connection.

[LytchettNM]

If I was you at this point I would remove the edge switch (I know it a lot of hassle) take that switch to the core and plug in with a patch cable.

If it works then problem is with the fibre run if does not well something to do with switch config or hardware but you will have an answer and can then plan you next step.

Saying that do you have spanning tree enabled if so just unplugging everything on the edge except the fibre might bring the link back up.

[Chaniel]

* new sfp modules didn't fix it.

@Shadow_Walker, did you actually swap the SFP modules? From your posts, it seems like you only reinserted the module on both ends and haven't swapped them out. Edited June 21, 2019 by Chaniel

[Davit2005]

Have you got Duplex mismatch on the ports, This can cause the link to fail.

[Shadow_Walker]

Thanks all for the responses. All sorted now, new fibre patch leads and some dust in the patch panel seems to be the cause. Everything back up and running now.