Cisco Catalyst 3750 Hardware Installation Manual page 58

Chapter 2 Product Overview
Front Panel Description
Voltages that present a shock hazard may exist on Power over Ethernet (PoE)
Warning
circuits if interconnections are made using uninsulated exposed metal
contacts, conductors, or terminals. Avoid using such interconnection methods,
unless the exposed metal parts are located within a restricted access location
and users and service people who are authorized within the restricted access
location are made aware of the hazard. A restricted access area can be
accessed only through the use of a special tool, lock and key or other means of
security.
The 10/100 ports on the on the Catalyst 3750-24PS and Catalyst 3750-48PS
switches provide PoE support for devices compliant with IEEE 802.3af and also
provide Cisco pre-standard PoE support for Cisco IP Phones and Cisco Aironet
Access Points.
Each of the Catalyst 3750-24PS switch 10/100 ports can deliver up to 15.4 W of
PoE. On the Catalyst 3750-48PS switch, any 24 of the 48 10/100 ports can deliver
15.4 W of PoE, or any combination of the 10/100 ports can deliver an average of
7.7 W of PoE at the same time, up to a maximum switch power output of 370 W.
On a per-port basis, you can control whether or not a 10/100 port on a Catalyst
3750-24PS or Catalyst 3750-48PS switch automatically provides power when an
IP phone or an access point is connected. CMS and the CLI provide two PoE
settings for each 10/100 port: Auto and Never.
When you select the Auto setting, the port only provides power if a valid powered
device, such as an IEEE 802.3af-compliant powered device, a Cisco pre-standard
IP phone, or a Cisco pre-standard Cisco access point, is connected to it. The Auto
setting is the default. However, when you select the Never setting, the port does
not provide power even if a Cisco IP phone or an access point is connected to it.
You also can connect a Cisco IP phone or Cisco Aironet Access Point to a Catalyst
Note
3750-24PS or Catalyst 3750-48PS switch 10/100 port and to an AC power source.
When the powered device is connected to the AC power source, it might begin to
use that as its primary power source. In that case, the 10/100 PoE port becomes
the backup power source for the powered device.
If the primary source fails, the second power source becomes the primary power
source. During the power transfer, an IP Phone might reboot or reestablish link
with the switch.
Catalyst 3750 Switch Hardware Installation Guide
2-10
78-15136-03