Cisco Systems 10000 Series Mode-Conditioning Gigabit Ethernet Patch Cord Description, 10-11

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Chapter 10 1-Port Gigabit Ethernet Half-Height Line Card Overview

SFP Module Configurations and Specifications

Mode-Conditioning Gigabit Ethernet Patch Cord Description

Amode-conditioning patch cord can be used with the SFP-GE-L= (SFP module) to allow reliable laser transmission between the single-mode laser source on the SFP module and a multimode optical fiber cable.

When an unconditioned laser source designed for operation on single-mode optical fiber is directly coupled to a multimode optical fiber cable, an effect known as differential mode delay (DMD) might result in a degradation of the modal bandwidth of the optical fiber cable.

This degradation results in a decrease in the link span (the distance between a transmitter and a receiver) that can be supported reliably. The effect of DMD can be overcome by conditioning the launch characteristics of a laser source. A practical means of performing this conditioning is to use a device called a mode-conditioning patch cord.

A mode-conditioning patch cord is an optical fiber cable assembly that consists of a pair of optical fibers terminated with connector hardware. Specifically, the mode-conditioning patch cord is composed of a single-mode optical fiber permanently coupled off-center (see Offset in Figure 10-4) to a graded-index multimode optical fiber. Figure 10-4shows a diagram of the mode-conditioning patch cord assembly.

Figure 10-4 Mode-Conditioning Patch Cord Assembly for an SFP Module

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RX TX

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Offset

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84159

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Gray color identifier

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Single-mode bar

 

 

 

 

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To Gigabit Ethernet interface

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Offset

 

 

 

 

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Beige color identifier

 

 

 

 

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Multimode bar

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To cable plant

 

 

 

 

The mode-conditioning patch cord assembly is composed of duplex optical fibers, including a single-mode-to-multimode offset launch fiber connected to the transmitter, and a second conventional graded-index multimode optical fiber connected to the receiver. The use of a plug-to-plug patch cord maximizes the power budget of multimode 1000BASE-LX and 1000BASE-LH links.

The mode-conditioning 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 cores. The solution is to launch light from the laser at a precise offset from the center, which is accomplished by using the mode-conditioning patch cord. At the output of the patch cord, the SFP-GE-L= is compliant with the IEEE 802.3z standard for 1000BASE-LX.

Go to Chapter 16, “Preparing for Installation” to begin the installation or replacement of the line card. For troubleshooting information, see Chapter 18, “Troubleshooting the Installation.”

 

 

Cisco 10000 Series Routers Line Card Hardware Installation Guide

 

 

 

 

 

 

OL-6773-04

 

 

10-11

 

 

 

 

 

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Contents ESR-HH-CARRIER= Line Card SummaryDescription Minimum Cisco IOS Release ESR-HH-1GE=10-2 PRE-11 Software and Hardware CompatibilityLine Card, Router, and Processor Compatibility Line Card Cisco10-4 LEDsLED Label Color State Meaning 10-5 Physical SpecificationsDescription Specifications Link10-6 Slot Locations10-7 Cables and Connectors10-8 Type SFP Module Configurations and SpecificationsSpecification Description Product ID10-10 GLC-ZX-SM= SMF10-11 Mode-Conditioning Gigabit Ethernet Patch Cord Description10-12
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