Signal Loss In Multimode And Single-Mode Fiber-Optic Cable For The Srx5400 Services Gateway; Attenuation And Dispersion In Fiber-Optic Cable For The Srx5400 Services Gateway - Juniper SRX5400 Hardware Manual

Table 43: Cable and Wire Specifications for Routing Engine Management and Alarm Interfaces
Port Cable Specification
Routing Engine RS-232 (EIA-232) serial
console or auxiliary cable
interface
Routing Engine Category 5 cable or
Ethernet interface equivalent suitable for
100Base-T operation
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable for the
SRX5400 Services Gateway
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.
Attenuation and Dispersion in Fiber-Optic Cable for the SRX5400 Services
Gateway
Correct functioning of an optical data link depends on modulated light reaching the receiver with enough
power to be demodulated correctly. Attenuation is the reduction in power of the light signal as it is
transmitted. Attenuation is caused by passive media components, such as cables, cable splices, and
connectors. While attenuation is significantly lower for optical fiber than for other media, it still occurs in
both multimode and single-mode transmission. An efficient optical data link must have enough light available
to overcome attenuation.
Cable/Wire Supplied
One 6-ft (1.83-m) length
with RJ-45/DB-9
connectors
One 15-ft (4.57-m) length
with RJ-45/RJ-45
connectors
Maximum Routing Engine
Length Receptacle
6 ft (1.83 m) RJ-45 female
328 ft (100 m) RJ-45
autosensing
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