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Cisco 2900 Series and 3900 Series Hardware Installation Guide
OL-18712-02
Chapter 1 Overview of the Routers
Hardware Features
Module and Router Power Consumption
Cisco 2900 series and Cisco 3900 series ISRs have energy efficiency features that reduce power
consumption. Some of the energy efficiency features are controlled by the hardware, whereas other
energy efficiency features are controlled by the software.
Hardware Features
• High-efficiency AC power supplies.
Software Features
• See the Configuring Power Efficiency Management module in the Cisco 3900 Series, 2900 Series,
and 1900 Series Integrated Services Routers Software Configuration Guide at Cisco.com. Learn
how to configure and manage power going to modules and peripherals.
Fans, Ventilation, and Airflow
The Cisco 2911 and Cisco 3900 series ISRs have optional fan filters that are easy to replace. The filters
may be used to meet Network Equipment Building Systems (NEBS) requirements, or to operate in dusty
environments. When a filter becomes dirty, discard it and replace it with a new one. See the “Replacing
a Fan Tray or Air Filter” section on page 5-45.
Fan speeds are controlled by the fan speed controller circuitry. To minimize noise, the fans operate at
one of several predetermined speeds and are dependent on the input ambient air temperature.
3945 X X X X X — — X X —
3945E X X X X X — — X X —
1. Must have RPS or POE boost installed.
2. Internal RPS means that and additional power supply can be added to the PS2 slot.
3. Uses external Cisco Redundant Power System 2300 with an adapter inserted in the chassis.
4. Dual DC means two separate DC inputs to the same power supply.
5. Uses Cisco Redundant Power System 2300 as 100% power boost. Internal power supply does not supply any boost. In this configuration there is no POE
redundancy.
Table 1-10 Cisco 2900 series and Cisco 3900 series POE Power Ratings
Router Model
Power Supply 2901 2911 2921 2951 3925 3925E 3945 3945E
Internal POE 130 W 200 W 280 W 370 W 520 W 520 W 520 W 520 W
Internal POE
Boost
— — — — 1040 W 1040 W 1040 W 1040 W
External POE
Boost
— 750 W 750 W 750 W — — — —
Table 1-9 Cisco 2900 Series and Cisco 3900 Series Field Replaceable Unit Power Options (continued)
Router
Model AC
AC +
POE DC Hot Swap
1
Internal
RPS
2
External
RPS
3
Dual DC
4
Internal POE
Internal
POE Boost
External
POE Boost
5