Calculating Power Budget For Fiber-Optic Cable For M Series, Mx Series, And T Series Routers; Calculating Power Margin For Fiber-Optic Cable For M Series, Mx Series, And T Series Routers - Juniper Networks Hardware Manual

M120 Multiservice Edge Router Hardware Guide
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Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series Routers

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Calculating Power Margin for Fiber-Optic Cable for M Series, MX Series, and T Series Routers

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Fiber-Optic and Network Cable Specifications for the M120 Router on page 241
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable for the M120 Router on
page 242
Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 244
Calculating Power Margin for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 244
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 M120 Router on page 241
Attenuation and Dispersion in Fiber-Optic Cable on M Series, MX Series, and T Series
Routers on page 243
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable for the M120 Router on
page 242
Calculating Power Margin for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 244
After calculating a link's power budget you can calculate the power margin (
represents the amount of power available after subtracting attenuation or link loss (
from the power budget ( P
B
P = P – LL
M B
A greater than zero indicates that the power budget is sufficient to operate the receiver.
P
M
) and minimum receiver sensitivity (
P
T
). A worst-case estimate of
P
P
), which
P
M
P assumes maximum LL :
M
Copyright © 2010, Juniper Networks, Inc.
),
B
):
R
LL )