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Fiber Trouble

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13 replies

by tech010

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I just connected 2 of my company's buildings via fiber. All works well except when we try to transfer large databases from one building to another, the connection then times out. I also notice that when I ping with packets of 2000b or larger, about 10 go through, but then every once in a while, they time out. I changed the fiber module jumper from Full to Half duplex, this seemed to help a little but we're still having trouble. This is single mode fiber and the buildings are close. Can anyone please help, do I need a fiber attenuator? Thanks.

13 replies

by piaconis

What kind of fiber are you using? Are you routing the packets, or just switching them? You may want to check that the maximum transmission unit (MTU) size is compatible wih your particular medium.

by maelgwyn

Ok so we have this:

B1 --- SM --- B2

HAve you checked the cable? The cable could be degrading the packets, but I doubt it.

So therefore, I would set the data bursts that the line would take, since it sounds like it could be anything from the LEDs to the cable to the sytem itself. Also have you tried to just check the segment by disconnecting everything but the 2 computers? It would be a problem with too much traffic on the segment (background)

Just a thougfht

Maelgwyn

by tech010

We're using single mode fiber. We're not routing packets, we're switching them and the switch is unmanageable. All of the systems in my building are having the same issues. Thanks. I ordered a new fiber module for the switch since I recently noticedthat we're receiving traffic fine, sending is where the issues come in. Anymore suggestions would be great. Thanks a lot.

by gigelul

You have on both ends of the fiber the same module speed (10, 100 or 1000Mb)?
You tried other pair of fiber?

by gigelul

We have many fiber connections in company area, but I don't have any problems and we use equipment/modules from the same manufacturer. I don't think that an attenuator will help you. Maybe you have an incompatibility between modules and switches, one switch have some problems or you need a firmware update for switches (read again fiber module specifications).

by tech010

Fiber is at 100/mb on each end. I replaced the module, and tried the other pairs. Could an attenuator resolve this? Could the signal be too strong for the close proximity?

by armylanman

You said receiving fine but sending bombing out.

Try switching the fibers from send to receive and the same on the other end. If it is a media problem the problem should reverse itself with the fibers, meaning you should then have problems receiving but not sending. If the problem follows one strand of fiber the media is the likely culprit.

If not I would look at the transceiver/fiber module.

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