Power Flow; Power Over Ethernet - Cisco Catalyst 4500e Series Installation Manual

System Architecture

Power Flow

Figure 1-17
Figure 1-17
Fan
tray
Power enters the switch through the power supplies. Several types of power supplies are available,
depending on the power needs for your system and the power type available on your site. All power
supplies provide a 3.3 V circuit (shown as a dash-dot line) to the components on the backplane and a
12 V circuit (shown as a solid line) that is carried over the backplane to the fans, supervisor engine, and
switching modules. Power supplies that support PoE (1300 W AC, 2800 W AC, 4200 W AC or 1400 W
DC) also provide a –48 V circuit (shown as a dashed line) to PoE-enabled switching modules, which is
then available to the powered device connected to the switching module.
The Supervisor Engine II-Plus TS has internal DC-to-DC converters that use the 12 V circuit to provide
Note
PoE to powered devices connected to the Supervisor engine only. If your system has a Supervisor Engine
II-Plus TS in slot 1, you still need a PoE-enabled power supply to provide PoE to the other slots.
All Catalyst 4500 E-series switches support dual power supplies, configurable for combined mode or
redundant mode. In combined mode, the switch has available the combined rated wattage of both power
supplies, less some expected efficiency loss. In redundant mode, one power supply provides power to
the system and the other supply is on standby should there be a failure in either the power supply or the
input voltage source it is connected to.

Power over Ethernet

The Cisco Catalyst 4500 E-series switches support the 802.3af standard for PoE on 10/100 or
10/100/1000 ports, enabling customers to support telephones, wireless base stations, video cameras, and
other appliances. PoE makes it possible to place devices in unique locations without having to provide
Catalyst 4500 E-Series Switches Installation Guide
1-32
shows power ingress and flow through the system.
Power Flow
Ingress to PS
PS1
Backplane
12 V
3.3 V
48 V
Ingress to PS
PS2
Supervisor engine
Switching module
Switching module
Chapter 1 Product Overview
IP
OL-13972-01