Inline Power Management Modes; Power Requirements - Cisco WS-C2950SX-48-SI Configuration Manual

Understanding How Inline Power Works

Inline Power Management Modes

Each port is configured through the CLI, SNMP, or a configuration file in one of the following modes
(configured through the set port inlinepower CLI command):
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Each port has a status that is defined as one of the following:
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Power Requirements

Each powered device has different power requirements.
different classes of IP phones and several other powered devices. The supervisor engine initially
calculates the power allocation for each port based on the per-port configuration and default power
allocation. If the correct amount of power is determined from the CDP messaging with the
Cisco-powered device, the supervisor engine reduces or increases the allocated power for any ports that
are set to Auto mode. Allocated power is not adjusted for ports that are set to Static mode.
For example, the default allocated power is 7 W for a Cisco IP Phone requiring 6.3 W. The supervisor
engine allocates 7 W for the Cisco IP Phone and powers it up. After the Cisco IP Phone is operational,
it sends a CDP message with the actual power requirement to the supervisor engine. The supervisor
engine then decreases the allocated power to the required amount if the port is set to Auto mode.
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
28-12
Auto—The supervisor engine directs the switching module to power up the port only if the switching
module discovers that the phone and the switch have enough power. You can specify the maximum
wattage that is allowed on the port. If you do not specify a wattage, then the switch delivers no more
than the hardware-supported maximum value.
Static—The supervisor engine directs the switching module to power up the port to the wattage you
specify only if the switching module discovers the phone. You can specify the maximum wattage
that is allowed on the port. If you do not specify a wattage, then the switch allows the
hardware-supported maximum value. The maximum wattage, whether determined by the switch or
specified by you, is preallocated to the port. If the switch does not have enough power for the
allocation, the command will fail.
Off—The supervisor engine does not direct the switching module to power up the port even if an
unpowered phone is connected.
on—Power is supplied by the port.
off—The power is not supplied by the port.
Power-deny—The supervisor engine does not have enough power to allocate to the port, or the
power that is configured for the port is less than the power that is required by the port. The power is
not being supplied by the port.
err-disable—The port cannot provide power to the connected device that is configured in Static
mode.
faulty—The port failed diagnostic tests.
Chapter 28
Table 28-4 lists the power requirements for the
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Release 8.1
Power Management
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