Calculating The J-Ex8200 Switch Fiber-Optic Cable Power Budget - Dell PowerConnect J-EX8216 Hardware Manual

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Calculating the J-EX8200 Switch Fiber-Optic Cable Power Budget

NOTE: We recommend that you maintain N +1 or N+N power supplies in your
switch at all times. Replace failed power supplies immediately to prevent
unexpected failures.
Power management raises a minor alarm if the number of online power
supplies in your switch is less than the number required to maintain the
configured power redundancy (N+1 or N+N). If the problem is not corrected
in 5 minutes, a major alarm is issued.
Power management raises a major alarm if the number of online power
supplies in your switch is less than N power supplies. Power management
provides power to line cards in priority order until power is exhausted. The
remaining line cards are powered off.
If a new line card is installed in an operational switch, power management
does not power on the line card if the increased power demand exceeds the
total available power, including redundant power. If redundant power is used
to power on the line card, a minor alarm is raised, which becomes a major
alarm in 5 minutes if the condition is not corrected.
AC Power Supply in a J-EX8200 Switch on page 39
Understanding Power Management on J-EX Series Switches
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 (
link:
Determine values for the link's minimum transmitter power (
1.
sensitivity ( ). For example, here, (
P
R
decibels are referred to one milliwatt (dBm).
= –15 dBm
P
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 (
2.
Chapter 7: Planning Power Requirements
) and ( ) are measured in decibels, and
P P
T R
) by subtracting ( ) from (
P P
B R
P ) for the
B
) and minimum receiver
P
T
):
P
T
91