Mode-Conditioning Patch Cord - Cisco 6513 - Catalyst Switch Installation Manual

Chapter 3 Installing Ethernet Switching Modules

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
a graded-index multimode optical fiber.
mode-conditioning patch cord assembly.
Figure 3-17
2
RX
3
1
3
5
7
9
OL-6265-03
Mode Conditioning Patch Cord with SC (GBIC Transceiver) Connector
1
TX
4 5
Beige color identifier
RX (receiver)
Blue color identifier
Single-mode fiber (SMF)
To cable plant
Figure 3-17 and Figure 3-18
6
/ /
/ / / /
Offset
7 8 6
2 To Gigabit Ethernet interface
4 TX (transmitter)
6 Multimode fiber (MMF)
8
Offset junction
Catalyst 6500 Series Ethernet Modules Installation Guide
Attaching the Network Interface Cables
Figure 3-17 and Figure
show a diagram of the
1
1
3-18) to
9
3-23