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netcmhFlag for United States of America asked on

Inter Floor Fiber Connect help


I have a pair of AT-MC101XLs. These are Fast Ethernet 100BASE-TX to 100BASE-FX (ST) Multi-Mode Fibre (2km), Stand-Alone Media Converters. Details can be found at http://www.alliedtelesis.com/p-2217.html.

I am trying to connect 2 floors together. I understand that the building fiber conduit is a straight through. However, when I attempt to test the connection from a laptop connected by ethernet to this media converter to another laptop connected by ethernet to the other media converter, I can't seem to get them to work.

The connection diagram is attached.

I understand that for this to work, I need to cross the fibers. Meaning Rx from one floor should go to Tx of the other floor.

I've tried swapping cables to ensure that it's not the cables. With only being able to test with the fibers coming from the media converter to the fiber panel, here's what my tests have given me:

Destination host unreachables when fibers not crossed.
Request timed out when fibers crossed.

I understand that in this situation, the Request timed out is a better error than the Destination host unreachable one.

I'm sure this is a simple fix, but I seem to be overlooking it. Any second set of eyes to help me along my way would be very appreciated.

Network ManagementNetworking Hardware-OtherNetworking

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8/22/2022 - Mon


From each patch panel you connected ST patch cord and connect directly to media converter.
Once you connected fiber cable perfectly link light will start blink .Then connect cat.6 cable and try to ping.If you have any doubt about cable ,basic link check you can do with normal red laser light.

What are you using to test?  Ping?  Do you have firewall enabled on the destination PC?

If you connect the PC's to a switch on the same floor can you get them to communicate?

Lights are blinking on both the converters. I do not have a laser light test equipment.

Yes, I'm using ping. No firewall on either PC. I can get the PCs to communicate when:
1. they are connected to the same hub.
2. they are connected directly over fiber through the media converters
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So the only time it does not work is when you are going through the patch panels?

Do you have the same fiber type between the media converters and patch panels as you do between the patch panels.

What is the distance between the floors and what type of fiber?  MM or SM?

Yes, it doesn't work going through the fiber panels.

The building conduit is something that we're not fully aware of. I don't know what type of fiber is used there. The conduit terminates on both the floors in question at similar fiber panels.

I asked about the distance. It is close to a 100 ft. The fiber I'm using is most probably an MM. I don't see any particular markings on the cable itself to be able to ID it properly.

I would verify what type of fiber.

If the types of fiber are not the same then it will not work.  What marking can you see on the fibre patch cable and on the fibre between the patch panels.

One thing you could do is download and install Wireshark on both computers and do a packet capture to see if anything that looks remotely valid is being passed.
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Well they're both orange, so I would say MMs. & It does say MM on both.

Does it have numbers like  62.5/125 or 50/125?

Link up both converter means your fiber link is up.you can test the link in converter there is a small switch once it press .it will automatically test the link.But normal condition ,means working time that switch you need to press again. then converter goes to normal mode.yhen only converter will work.

Thank you.
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O.K, it looks like the all cables are MM and the same size.

Run the test sanjayrajt said to run and it passes then run a packet capture with Wireshark.

Hopefully between those we can figure out something.

So, press the button on one converter, or both? They need to be connected directly or through the conduit? First time testing this way, please guide.
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Solved it myself. Conduit pair was probably broken, tested with another pair and it works. Thanks to all the experts who wanted to help.