X2-10GB-LX4 Mode Conditioning Patch or Not 62.5micron Fiber

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Sep 27th, 2010
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I keep reading different things across the web.  We are swapping out our SUP 720's with the newer VSS Sup 720's for the VSS technology.  During the process we are going to start bringing 10Gb in.  We have an existing FDDI (62.5 Micron MM) fiber plant.  We purchased these with the X2-10GB-LX4 fiber modules designed to do 300m over 62.5 Micron fiber...  Do we need a mode conditioning patch cord on each end?  It would seem Cisco says yes or use the GBIC over single mode?  I thought this was a multi-mode X2 module...  I'm quite confused!!! 

Correct Answer by Tom Randstrom about 6 years 9 months ago

If you use the X2-10GB-LX4 transciever with 62.5 micron MMF, you need a Mode Conditioning Patchcord (MCP), part number CAB-GELX-625= or similar, on each end. 


The -LX4 module it designed for MMF.  In order to get a 10G signal through 300m of multimode fiber (which was originally designed for short, low bit rate paths) the LX4 module engineers used 4 coupled laser transmitters to send the information through the fiber.  The Mode Conditioning Patchcords focus this laser light into the optimum section of the multimode fiber's core, so that it can reach the distant receiver and be successfully decoded.


This module, without the use of the MCPs, can be used on singlemode fiber (SMF).  But, this module is more expensive that a standard SMF transceiver (LR or LRM) due to its use of 4 lasers and the WDM multiplexing integrated into the transceivers.  


Does this help at all?


Tom

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rhornberger Mon, 09/27/2010 - 12:22
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I forgot one other piece of info...  The runs are appx 200m or tested at 681 feet...  I'm really questioning the need for MCP's given the distance...  I thought the reason for the MCP's on this fiber module was too much power behind the light on short runs, the incorrect amount of dispersion, etc.

Correct Answer
Tom Randstrom Mon, 09/27/2010 - 12:31
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If you use the X2-10GB-LX4 transciever with 62.5 micron MMF, you need a Mode Conditioning Patchcord (MCP), part number CAB-GELX-625= or similar, on each end. 


The -LX4 module it designed for MMF.  In order to get a 10G signal through 300m of multimode fiber (which was originally designed for short, low bit rate paths) the LX4 module engineers used 4 coupled laser transmitters to send the information through the fiber.  The Mode Conditioning Patchcords focus this laser light into the optimum section of the multimode fiber's core, so that it can reach the distant receiver and be successfully decoded.


This module, without the use of the MCPs, can be used on singlemode fiber (SMF).  But, this module is more expensive that a standard SMF transceiver (LR or LRM) due to its use of 4 lasers and the WDM multiplexing integrated into the transceivers.  


Does this help at all?


Tom

rhornberger Mon, 09/27/2010 - 12:45
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Great response...  Interesting, I chose this LX4 because the guy I bought the SUP's off of had an overstock of the LX4 modules and made them cheaper than any other module...  So I could use my existing SMF plant instead...  Quite interesting...

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