Appendix E T640 Router Cable And Wire Guidelines And Specifications; T640 Network Cable Specifications And Guidelines; T640 Signal Loss In Multimode And Single-Mode Fiber-Optic Cable - Juniper T640 Hardware Manual

APPENDIX E
T640 Router Cable and Wire Guidelines
and Specifications

T640 Network Cable Specifications and Guidelines

T640 Signal Loss in Multimode and Single-Mode Fiber-Optic Cable

Copyright © 2010, Juniper Networks, Inc.
T640 Network Cable Specifications and Guidelines on page 361
T640 Routing Engine Interface Cable and Wire Specifications on page 365
T640 Signal Loss in Multimode and Single-Mode Fiber-Optic Cable on page 361
T640 Attenuation and Dispersion in Fiber-Optic Cable on page 362
T640 Attenuation in SONET/SDH PICs on page 362
Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 363
Calculating Power Margin for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 363
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. Compared with multimode fiber, single-mode fiber has higher
bandwidth and can carry signals for longer distances. It is consequently more expensive.
For information about the maximum transmission distance and supported wavelength
range for the types of single-mode and multimode fiber-optic cable used by PICs on the
T640 router, see the T640 Core Router PIC Guide. Exceeding the maximum transmission
distances can result in significant signal loss, which causes unreliable transmission.
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