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

Question

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!!! 

Answer 1

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