Installation guide

1-7
Catalyst 3560 Switch Hardware Installation Guide
OL-6337-03
Chapter 1 Product Overview
Front Panel Description
When set for autonegotiation, the port senses the speed and duplex settings of the attached device and
advertises its own capabilities. If the connected device also supports autonegotiation, the switch port
negotiates the best connection (the fastest line speed that both devices support and full-duplex
transmission if the attached device supports it) and configures itself accordingly. In all cases, the
attached device must be within 328 feet (100 meters).
Warning Voltages that present a shock hazard may exist on Power over Ethernet (PoE) 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. Statement 1072
The10/100 ports on the Catalyst 3560-24PS and 3560-48PS switches and the 10/100/1000 ports on the
Catalyst 3560G-24PS and 3560G-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 3560-24PS switch 10/100 ports or the Catalyst 3560G-24PS switch 10/100/1000
ports can deliver up to 15.4 W of PoE. On the Catalyst 3560-48PS or 3560G-48PS switches, any 24 of
the 48 10/100 or 10/100/1000 ports can deliver 15.4 W of PoE, or any combination of the 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 Catalyst 3560 PoE port automatically provides
power when an IP phone or an access point is connected. The Cluster Management Suite (CMS),
Network Assistant, and the CLI provide two PoE settings for each 10/100 or 10/100/1000 PoE port: Auto
and Never.
When you select the Auto setting, the port provides power only 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.
Cisco enhanced power negotiation allows some powered devices, such as the Cisco 7970G IP Phone, to
operate in high-power mode on Catalyst 3560 PoE switches. The powered device and the switch
negotiate through power-negotiation Cisco Discovery Protocol (CDP) messages for an agreed-upon
power-consumption level. The negotiation allows a high-power Cisco powered device that consumes
more than 7 W to operate at its highest power mode. The powered device first boots up in low-power
mode, consumes less than 7 W, and negotiates to obtain enough power to operate in high-power mode.
The device changes to high-power mode only when it receives confirmation from the switch. High-power
devices can operate in low-power mode on switches that do not support power-negotiation CDP.
For information about configuring and monitoring PoE ports, see the switch software
configuration guide.
Note You also can connect a Cisco IP Phone or Cisco Aironet Access Point to a Catalyst 3560 PoE switch
10/100 or 10/100/1000 port and to an AC power source for redundant power. The powered device might
switch to the AC power source as its primary power source upon being connected to it. In that case, the
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 to the powered
device. During the power transfer, an IP phone might reboot or reestablish link with the switch.