Cisco Catalyst 2955 Series, Hardware Installation Manual

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Catalyst 2955 Hardware Installation Guide
78-14944-03
Chapter 2 Overview
Front-Panel Description
In dual-power mode, the switch draws power from the power supply with the
higher voltage. If the primary power supply fails in dual-power mode, the
alternate power supply gives power to the switch.
The power status LEDs show whether the individual power supplies are receiving
power and functioning properly.
Table 2-1 lists the LED colors and meanings.
Note
The power status LEDs show that power is not present on the switch if the power
input drops below 17 V. The power status LEDs only show that power is present
if the voltage at the switch input exceeds 18.5 V. The 1.5 V difference, or
hysteresis, ensures that the power status LEDs do not oscillate at values near 18 V.
In dual-power mode, the power status LEDs show status for both power inputs,
VA and VB.
For information about the power LED colors during the power-on self-test
(POST), see the
“Powering On the Switch and Running POST” section on
page 3-13 .
10/100 Port Status LEDs
Each 10/100 port has a port status LED, also called a port LED, shown in
Figure 2-7 and Figure 2-8 . These LEDs display information about the switch and
the individual ports, shown in Table 2-2 .
Table 2-1 Power Status LEDs
Color System Status
Off System is not powered up.
Green Power present on associated contact.
Red Power not present on associated contact.