Fiber connectivity issue

Hello,

I have 2 floors that need to connect to each other. I have fiber conduit running between them.

I have a pair of media converters which translate ethernet to fiber and vice versa.

I also have Cisco switches with SFP - GLC-SX-MMs on either end.

A laptop connected to a media converter over ethernet on one floor can talk with a laptop connected to the other media converter over ethernet on the other floor. The cables connecting the media converters to the fiber conduit are ST ended and have the following markings: Orange cable: BERK-TEK OPTICAL FIBER CABLE - 62.5/125 - ICR0X0 - FDDI TYPE OFNR (UL) CSA OFN FT-4 75C 04/94 079636 FEET.

However, I cannot get a laptop connected to a media converter on one floor to talk with the switch connected on the other floor over an LC-ST-MM cable into the with the following markings: Orange cable: CORNING OPTICAL FIBER 62.5/125 MM-2. O*4. 1 04/2013 FIBER OF (UL) OFNR ROHS 00683M

The first scenario has the same kind of cables on both floors. The second scenario has the 2 kinds of cables - one from scenario one and the other from senario two.

I've swapped out cables, had the fiber panel connectors cleaned and refitted (which helped lessen the dB variation) and even swapped out the SFP - GLC-SX-MMs and their respective ports. I still cannot get this to work.

Any viable ideas will be much appreciated.

Thanks.
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netcmhAsked:
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scrabyCommented:
i don't know much about fiber but don't you have indicator lights on the media converter that would tell you if you have a connection or not?  perhaps similar to the lights on an ethernet connector on a switch or nic
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netcmhAuthor Commented:
I do have the link lights up blinking away.
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TomRScottCommented:
From your description, there should not be an issue with the fiber itself (not the run nor the patch cables).

I would look at the lights too.

However, my main areas of concern are:
Switch IP Address: Make sure it is the same as the laptop(s). Also, try connecting a laptop directly to the switch by a copper port just to be sure it is not IP or the switch itself.

The media converters: One has to be careful with mating media converters.  Just because they are both multi-mode does not mean they mate up well.  In particular, check out the wave length specifications, they should be the same on both ends. It is also highly advisable to match up loss and the specified maximum distance.  You have already matched up the fiber diameter.
- Tom
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netcmhAuthor Commented:
The switch's interface does not come up with scenario two. It's IP address is the same as the laptop I was testing earlier with on the floor. The laptop connected to this switch on an ethernet port lights up just fine, but not on the SFP port. I have a 4507 with a WS-X4612-SFP-E 12 port GBIC blade with 2 ports available for this project. I've tested both the ports with different SFPs and they still won't come up. They're not shutdown on the switch.
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Dave BaldwinFixer of ProblemsCommented:
What brand and model are the media converters?  I would suspect that they are using a proprietary protocol on the fiber ports so they can only talk to each other.
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TomRScottCommented:
Have you mated up the media converters (this includes the SFP media converters) based matching up all the relevant specifications.

Also, maybe bypass linking the laptop directly to a media converter (that may not match the SFP on the other end) and just insert a pair of matching SPFs on the switches and test accessing the switches by jacking the laptop into each switch (testing the opposite switch).

 - Tom
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netcmhAuthor Commented:
Allied Telesyn AT-FS201 media converters. Their spec sheet doesn't say anything about a proprietary protocol.

What do you mean by mated up?
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kzin_xxxxCommented:
I would forget the media convertors for now , and concentrate on the physical layer between switches.

What length is the inter-floor fibre run ?
What type of fibre is it , single mode or multi mode , and what core if MM , 50/62.5 ?

If single , and you are using MM patch fibres , you will have problems.

If the run length is greater than 220m on MMF you will have problems.

62.5 micron into 50 micron core - well I've seen it done , but I wouldn't recommend it...

If the length and type are ok , all MMF and <220m , then plug an SFP into each switch and patch the fibres through. There will need to be a cross over of the fibres , but simply swap one end over when patching if it doesn't light up within 20 secs.

Once you have this up , then look at IP and vlans.
:-)
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kzin_xxxxCommented:
One more thing - SFP optics are typically 1Gb (or 10Gb) on speed. They don't negotiate down.

Are your MC's 1Gb optics ? - if so they should also work either back to back or one into a switch (&SFP) directly.

:-)
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TomRScottCommented:
To "mate" or match up media converters they must use the same wave length(s) and speed (10/100, 1G, etc.).

They should also have the same decibel loss and maximum distance.

 - Tom
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Dave BaldwinFixer of ProblemsCommented:
The data sheet for the Allied Telesyn AT-FS201 says the fiber port is 100FX and it looks like the CISCO switch is 1000BASE-SX.  If there is no negotiation, the speeds aren't compatible.
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netcmhAuthor Commented:
The inter-floor fiber run is approximately 250 feet.

Fiber type : MM 62.5/125 all the way through

I'll try the SFPs on either end. I was hoping to have the media converter on one end and the SFP on the switch on the other.

Media converters are 10/100.

Made sure the dip switch settings are the same on both MCs. Had the dB loss checked and fixed before we started.
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TomRScottCommented:
The fiber sounds fine. Although copper would have sufficed (unless you have a massive interference issue in the building) with much less cost and being that you are new to fiber, less hassle too.

Sounds like you have mismatched equipment. Dave hit on another matching issue regarding one of the switches and one of the SFPs.

Bottom Line: You need to match up the specifications of the electronics and optics. Until you look at that and rectify any issues there you are spinning your wheels.

 - Tom
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