It Should work, but it won't

[psiegling]

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We have a new install of OM3 fiber between buildings. Distance is around 600 FT. One one end is a 4510RE running cat4500e-UniversalK9-M, ver 03.02.00.SG (fc4). Connecting to line card WS-X4306-GB with a WS-5486-LX/LH GBIC in port 3.
On the other end, and 3750-24-PS switch with a GLC-LH-SM= module. Code on the 3750 is: c3750-ipbasek9-mz.122-55.SE4
The fiber is tested good. Notice the GLC-SM-LH is showing at and LX module in the 3750 show inventory. Have replaced module with know working modules and tested module on know working links. All tests are positive. Does not appear to be configuration issues on the interfaces.

Any thoughts on what to do next. Compatibility matrix says this should be good. Are my modules not good for OM3, even though Cisco says they are?

[John Blakley]

Have you checked that the pairs aren't reversed? The cable can check good, but it won't come up if the tx/rx is reversed. You'd have to physically reverse one end of the patch cable.

HTH,
John

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[psiegling]

All Combinations of TR/RX have been tested. All elements are as they should be, but still, no link. Am thinking of using a GLC-MM-SX module on the 3750 side. Just for giggles and grins. Those are usually the attempts that make it work. Go figure.

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[acampbell]

Hi,

You are trying run single mode gbics accross a multimode OM3 50/125 fibre.

You will need to deploy conditioning fibre patchcords to offset the the single mode signal.

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/product_bulletin_c25-530836.html

Regards,
Alex.
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[Leo Laohoo]

Duplicate posts. 

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