Cisco Systems 7600 manual LX/LH GBIC and MMF Cable Considerations, Patch Cord, B-16

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-8shows a typical patch cord configuration.

Figure B-8 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 7600 Series Router Supervisor Engine and Route Switch Processor Guide
B-16	OL-10100-04