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B-16
Cisco 7600 Series Router Supervisor Engine and Route Switch Processor Guide
OL-10100-04
Appendix B Cable and Connector Specifications
LX/LH GBIC and MMF Cable Considerations
LX/LH GBIC and MMF Cable Considerations
The following sections describe the things you should consider if you are using a Supervisor Engine 2
with a long wavelength/long haul (LX/LH) GBIC with 62.5-micron diameter MMF cable.
Patch Cord
When using the long wavelength/long haul (LX/LH) GBIC with 62.5-micron diameter MMF on links
that span more than 984
feet (300 meters), a mode-conditioning patch cord is required. You must install
the 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.
Note We also recommend using a patch cord between the LX/LH GBIC and MMF cable for very short link
distances (10 to 100 meters). Without a patch cord, the link can have an elevated bit error rate (BER).
Note The patch cord is required to comply with IEEE standards. The 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
mode-conditioning patch cord. At the output end of the patch cord, the LX/LH GBIC complies with the
IEEE 802.3z standard for 1000BASE-LX.
Patch Cord Configuration Example
Figure B-8 shows a typical patch cord configuration.
Figure B-8 Patch Cord Configuration
1000BASE-LX/LH
port
Patch
panel
Link span greater than 984 ft
(300 m)
1000BASE-LX/LH
port
Rx
Tx
Patch
panel
Patch
cord
Building
cable plant
Tx
Rx
Patch
cord
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