Understanding Ex Series Switches Fiber-Optic Cable Signal Loss, Attenuation, And Dispersion - Juniper EX2300 Series Hardware Manual

• EX8208—Hardware Compatibility Tool page for EX8208
• EX8216—Hardware Compatibility Tool page for EX8216
• EX9251—Hardware Compatibility Tool page for EX9251
• EX9253—Hardware Compatibility Tool page for EX9253
Standards Supported by These Cables
The cables comply with the following standards:
• SFP mechanical standard SFF-843— see
• Electrical interface standard SFF-8432— see
• SFP+ Multi-Source Alliance (MSA) standards
Understanding EX Series Switches Fiber-Optic Cable Signal Loss,
Attenuation, and Dispersion
IN THIS SECTION
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable | 79
Attenuation and Dispersion in Fiber-Optic Cable | 80
To determine the power budget and power margin needed for fiber-optic connections, you need to
understand how signal loss, attenuation, and dispersion affect transmission. EX Series switches use
various types of network cable, including multimode and single-mode fiber-optic cable.
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable
Multimode fiber is large enough in diameter to allow rays of light to reflect internally (bounce off the
walls of the fiber). Interfaces with multimode optics typically use LEDs as light sources. However, LEDs
are not coherent light sources. They spray varying wavelengths of light into the multimode fiber, which
reflects the light at different angles. Light rays travel in jagged lines through a multimode fiber, causing
signal dispersion. When light traveling in the fiber core radiates into the fiber cladding (layers of lower
refractive index material in close contact with a core material of higher refractive index), higher-order
ftp:/ /ftp.seagate.com/sff/SFF-8431.PDF.
ftp:/ /ftp.seagate.com/sff/SFF-8432.PDF.
79