Cisco Systems 7609 manual Mode-Conditioning Patch Cord, Patch Cord Configuration Example

Appendix B Connector and Cable Specifications

Cable Specifications

Mode-Conditioning Patch Cord

When using the long wavelength/long-haul (LX/LH) GBIC with 62.5-micron diameter MMF, you must install a mode-conditioning patch cord (Cisco product number CAB-GELX-625 or equivalent) between the GBIC and the multimode fiber (MMF) cable on both the transmit and receive ends of the link. The patch cord is required for link distances greater than 984 feet (300 meters).

Note We do not recommend using the LX/LH GBIC and MMF without the patch cord for very short link distances of 33 to 328 feet (10 to 100 meters). The result could be an elevated bit error rate (BER).

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/LH GBIC complies with the IEEE 802.3z standard for 1000BASE-LX.

Patch Cord Configuration Example

Figure B-7shows a typical patch cord configuration.

Figure B-7 Patch Cord Configuration

Patch

cord

Rx

1000BASE-LX/LH port

Tx

	Building	Patch
	cable plant	cord
		Tx
Patch	Patch	1000BASE-LX/LH
panel	panel	port
		Rx
Link span greater than 984 ft
	(300 m)

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	Cisco 7609 Internet Router Installation Guide
OL-5079-04		B-13