Mode Conditioning Patch cable (MCP)

In some fiber optic applications, it is possible to use a long wavelength (1300 nm) single-mode transceiver with multimode fiber by placing a special device known as a mode conditioning patch (MCP) cable at both ends of the link. The MCP cable resembles a standard 2 meter jumper cable.

Because of the bandwidth limitations of multimode fiber, future multi-gigabit fiber optic interconnects will likely be based on single mode fiber cables. However, many current applications use multimode fiber extensively. There is a need to re-use the large installed base of multimode fiber as long as possible; the ability to continue using installed fiber with new adapter cards also facilitates migration to higher data rate links. The need to migrate from multimode to single mode fiber affects all of the major datacom applications:

• Using MCPs, it is possible to run LX FICON® channels over multimode fiber at reduced distances [550 meters (.31 miles)]. Although FICON is available in both multimode (SX) and single mode (LX) versions, future FICON enhancements which extend this protocol to multi-gigabit data rates will also require single mode fiber for distances beyond a few hundred meters.
• Coupling links for Parallel Sysplex® were originally offered as either 50 Mbyte/s data rates over 50 micron multimode fiber (using short wavelength 850 nm lasers) or 100 Mbyte/s data rates over single mode fiber (using long wavelength 1300 nm lasers). In May 1998 support for multimode fiber was withdrawn. There is a need to support 100 MByte/s adapter cards over the installed 50 micron multimode fiber to facilitate migration from the 50 Mbyte/s links.

This support will continue on coupling links using the LC interface; an MCP which adapts single mode LC to multimode SC Duplex is available for compatibility mode (1 Gbit/s) links.