Series Routers; Network Cable And Transceiver Planning; Calculating Power Budget For Fiber-Optic Cable For M Series, Mx Series, And T Series Routers - Juniper M7i Hardware Manual

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Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers
Related
Documentation
Copyright © 2019, Juniper Networks, Inc.
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.
The router uses optical lasers for SONET/SDH PIC single-mode interfaces. These optics
comply with IR-1 of Bellcore GR-253-CORE Issue 2, December 1995 and ANSI TI.105.06.
For information about the maximum transmission distances and wavelength ranges
supported by multimode and single-mode (ATM and SONET/SDH) PIC interfaces, see
the interface module reference for your device. Exceeding the maximum transmission
distances can result in significant signal loss, which causes unreliable transmission.
Fiber-Optic and Network Cable Specifications for the M7i Router on page 91
Attenuation and Dispersion in Fiber-Optic Cable on M Series, MX Series, and T Series
Routers on page 91
Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 93
Calculating Power Margin for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 94
To ensure that fiber-optic connections have sufficient power for correct operation, you
need to calculate the link's power budget, which is the maximum amount of power it
can transmit. When you calculate the power budget, you use a worst-case analysis to
provide a margin of error, even though all the parts of an actual system do not operate
at the worst-case levels. To calculate the worst-case estimate of power budget (
you assume minimum transmitter power (
P = P – P
B T R
The following hypothetical power budget equation uses values measured in decibels
(dB) and decibels referred to one milliwatt (dBm):
P = P – P
B T R
P = –15 dBm – (–28 dBm)
B
P = 13 dB
B
Fiber-Optic and Network Cable Specifications for the M7i Router on page 91
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable for the M7i Router on
page 92
Attenuation and Dispersion in Fiber-Optic Cable on M Series, MX Series, and T Series
Routers on page 91
Chapter 12: Network Cable and Transceiver Planning
) and minimum receiver sensitivity (
P
T
P ),
B
):
P
R
93