Mode-Conditioning Patch Cord
When using the long-wavelength and long-haul (LX and LH) GBIC with 62.5-micron diameter multimode
fiber (MMF), you must install a mode-conditioning patch cord (Cisco product number CAB-GELX-625 or
equivalent) between the GBIC and the MMF cable on both the transmit and receive ends of the link. A
mode-conditioning patch cord is required for 1000BASE-LX and LH applications over FDDI-grade, OM1,
and OM2 fiber-cable types. Mode-conditioning patch cords should not be used for applications over OM3
fiber cable (laser-optimized fiber cable). For more information about mode-conditioning patch cords, see the
Use of Mode Conditioning Patch Cables in Gigabit Ethernet and 10 Gigabit Ethernet Laser-Based Transmissions
bulletin available on Cisco.com.
We recommend that you use the LX and LH GBIC and MMF with the patch cord for short link distances
of 33 to 328 feet (10 to 100 meters) because not using the patch could result in an elevated bit error rate
(BER).
Note
The patch cord is required to comply with IEEE standards. IEEE found that link distances could not be met
with certain types of fiber-optic cable due to a problem in the center of some fiber-optic cable cores. The
solution is to launch light from the laser at a precise offset from the center by using the patch cord. At the
output of the patch cord, the LX and LH GBIC complies with the IEEE 802.3z standard for 1000BASE-LX.
Example: Patch Cord Configuration
Figure 44: Patch Cord Configuration
Installing the Patch Cord
Invisible laser radiation may be emitted from disconnected fibers or connectors. Do not stare into beams
or view directly with optical instruments. Statement 1051
Warning
To install the patch cord, perform these steps:
Cisco Catalyst 6807-XL Switch Hardware Installation Guide
OL-30656-01 95
Transceivers, Module Connectors, and Cable Specifications
Mode-Conditioning Patch Cord
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