Calculating The Ex Series Switch Fiber-Optic Cable Power Budget - Juniper EX4500 Hardware Manual

Related
Documentation

Calculating the EX Series Switch Fiber-Optic Cable Power Budget

Copyright © 2017, Juniper Networks, Inc.
The grounding cable that you provide for an EX4500 switch must be 14 AWG (2 mm
minimum 90°C wire, or as permitted by the local code.
NOTE: Grounding is provided to an AC-powered switch when you plug its
power supplies into grounded AC power receptacles.
WARNING: The switch is pluggable type A equipment installed in a
restricted-access location. It has a separate protective earthing terminal
provided on the chassis in addition to the grounding pin of the power supply
cord. This separate protective earthing terminal must be permanently
connected to earth ground for installations that require a separate grounding
conductor to the chassis.
AC Power Supply in EX4500 Switches on page 39
Installing an AC Power Supply in an EX4500 Switch on page 184
Calculate the link's power budget when planning fiber-optic cable layout and distances
to ensure that fiber-optic connections have sufficient power for correct operation. The
power budget is the maximum amount of power the link 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 for fiber-optic cable power budget (P
link:
Determine values for the link's minimum transmitter power (P
1.
sensitivity (P ). For example, here, (P
R
decibels are referred to one milliwatt (dBm).
P = –15 dBm
T
P = –28 dBm
R
NOTE: See the specifications for your transmitter and receiver to find the
minimum transmitter power and minimum receiver sensitivity.
Calculate the power budget (P
2.
–15 dBm – (–28 dBm) = 13 dBm
Chapter 7: Power Specifications and Requirements
) and (P ) are measured in decibels, and
T R
) by subtracting (P ) from (P
B R
2
),
) for the
B
) and minimum receiver
T
):
T
85