Cisco Systems 6500 manual Mode-Conditioning Patch Cord

Chapter 3 Installing Ethernet Switching Modules

Attaching the Network Interface Cables

Mode-Conditioning Patch Cord

A mode-conditioning patch cord is recommended for use with an LX/LH GBIC or an LX/LH SFP transceiver and MMF to allow reliable laser transmission.

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 3-7and Figure 3-8) to a graded-index multimode optical fiber. Figure 3-7and Figure 3-8show a diagram of the mode-conditioning patch cord assembly.

Figure 3-7 Mode Conditioning Patch Cord with SC (GBIC Transceiver) Connector

				6
		1	/ /	/ /	/ /	1
	2			Offset		9
RX	TX
3
	4	5	7	8	6	1

57011

1	Beige color identifier	2	To Gigabit Ethernet interface
3	RX (receiver)	4	TX (transmitter)
5	Blue color identifier	6	Multimode fiber (MMF)
7	Single-mode fiber (SMF)	8	Offset junction
9	To cable plant

Catalyst 6500 Series Ethernet Modules Installation Guide

OL-6265-04 3-13