Installation guide

Chapter 3 Switch Installation
Powering the Switch and Connecting Devices
3-26
Catalyst 3550 Multilayer Switch Hardware Installation Guide
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Connecting to the 10/100 Inline Power Ports
You can connect the Catalyst 3550-24PWR switch to a Cisco IP Phone through a
straight-through, twisted four-pair Category 5 cable. The rear panel of the Cisco
IP Phone might have more than one RJ-45 connector. Use the LAN-to-phone
connector to connect the IP phone to the Catalyst 3550-24PWR switch.
You can configure the 10/100 ports on the Catalyst 3550-24PWR switch to either
automatically provide inline power when a Cisco IP Phone or a Cisco Aironet
Access Point is connected or to never provide inline power even if an IP phone or
an access point is connected. The default setting is Auto.
Caution It takes a Catalyst 3550-24PWR 10/100 port up to 10 seconds to initially detect,
power up, and link to a Cisco IP Phone. If you disconnect the Cisco IP Phone
before link is established, you must wait 10 seconds before connecting another
network device (other than another IP phone) to that switch port. Failure to do so
can result in damage to that network device.
You also can connect the Cisco IP Phone or Cisco Aironet Access Point to a
Catalyst 3550-24PWR 10/100 port and to an AC power source for redundant
power. The power source to which the external device is first connected becomes
its primary power source, and the second power source is its backup. If the
primary source fails, the second power source becomes the primary power source
to the device. During the power transfer, the device might reboot or reestablish
link with the switch.
For information about Cisco IP Phones and Cisco Aironet Access Points, refer to
the documentation that came with your IP phone or access point.
Connecting to 100BASE-FX Ports
Caution To prevent ESD damage, follow your normal board and component handling
procedures when connecting to the 100BASE-FX ports.
The 100BASE-FX ports operate only at 100 Mbps and support both full- and
half-duplex mode. The half-duplex mode is the default setting. Autonegotiation is
not supported.