Juniper Networks M10, M5 manual Network Cable Specifications and Guidelines

Network Cable Specifications and Guidelines

connecting the DC power and grounding cables during initial installation, see “Connect Power to a DC-Powered Router” on page 66. For instructions on replacing the cables on an operating router, see “Disconnect and Connect DC Power” on page 108.

Power cords and cables must not block access to router components or drape where people could trip on them.

Network Cable Specifications and Guidelines

The various PICs supported on the router accept different kinds of network cable, including multimode and single-mode fiber-optic cable. For more information, see the following sections:

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Fiber Optic and Network Cable Specifications on page 48

Signal Loss in Multimode and Single-Mode Fiber-Optic Cable on page 48

Attenuation and Dispersion in Fiber-Optic Cable on page 49

Calculating Power Budget for Fiber-Optic Cable on page 49

Calculating Power Margin for Fiber-Optic Cable on page 50

Attenuate to Prevent Saturation at SONET/SDH PICs on page 51

Fiber Optic and Network Cable Specifications

The router supports PICs that use various kinds of network cable, including multimode and single-mode fiber-optic cable. For information about the type of cable used by each PIC, see the M5 and M10 Internet Routers PIC Guide.

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. LEDs are not coherent sources, however. 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, higher-order mode loss (HOL) results. Together these factors limit the transmission distance of multimode fiber compared to single-mode fiber.

Single-mode fiber is so small in diameter that rays of light can reflect internally through one layer only. Interfaces with single-mode optics use lasers as light sources. Lasers generate a single wavelength of light, which travels in a straight line through the single-mode fiber.

48M5 and M10 Internet Routers Hardware Guide