12-24
Catalyst 2975 Switch Software Configuration Guide
OL-19720-02
Chapter 12 Configuring Interface Characteristics
Configuring Ethernet Interfaces
For information about the output of the
show power inline
user EXEC command, see the command
reference for this release. For more information about PoE-related commands, see the
Power over Ethernet Switch Ports” section on page 38-13
. For information about configuring voice
VLAN, see
Chapter 14, “Configuring Voice VLAN.”
Budgeting Power for Devices Connected to a PoE Port
When Cisco powered devices are connected to PoE ports, the switch uses Cisco Discovery Protocol
(CDP) to determine the
actual
power consumption of the devices, and the switch adjusts the power
budget accordingly. The CDP protocol works with Cisco powered devices and does not apply to IEEE
third-party powered devices. For these devices, when the switch grants a power request, the switch adjusts
the power budget according to the powered-device IEEE classification. If the powered device is a
Class 0 (class status unknown) or a Class 3, the switch budgets 15,400 milliwatts for the device,
regardless of the actual amount of power needed. If the powered device reports a higher class than its
actual consumption or does not support power classification (defaults to Class 0), the switch can power
fewer devices because it uses the IEEE class information to track the global power budget.
By using the
power inline consumption
wattage
configuration command, you can override the default
power requirement specified by the IEEE classification. The difference between what is mandated by
the IEEE classification and what is actually needed by the device is reclaimed into the global power
budget for use by additional devices. You can then extend the switch power budget and use it more
effectively.
For example, if the switch budgets 15,400 milliwatts on each PoE port, you can connect only 24 Class 0
powered devices. If your Class 0 device power requirement is actually 5000 milliwatts, you can set the
consumption wattage to 5000 milliwatts and connect up to 48 devices. The total PoE output power
available on a 24-port or 48-port switch is 370,000 milliwatts.
Caution
You should carefully plan your switch power budget and make certain not to oversubscribe the power
supply.
Note
When you manually configure the power budget, you must also consider the power loss over the cable
between the switch and the powered device.
When you enter the
power inline consumption default
wattage
or the
no
power inline consumption
default
global configuration command, or the
power inline consumption
wattage
or the
no
power
inline consumption
interface configuration command this caution message appears:
%CAUTION: Interface
interface-id
: Misconfiguring the 'power inline consumption/allocation'
command may cause damage to the switch and void your warranty. Take precaution not to
oversubscribe the power supply.
It is recommended to enable power policing if the switch supports it.
Refer to documentation.
Step 5
show power inline
[i
nterface-id |
module
switch-number
]
Display PoE status for a switch or switch stack, for the specified
interface, or for a specified stack member.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Содержание 2975 - Catalyst LAN Base Switch
Страница 36: ...Contents xxxvi Catalyst 2975 Switch Software Configuration Guide OL 19720 02 ...
Страница 40: ...xxxviii Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Preface ...
Страница 62: ...1 22 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 1 Overview Where to Go Next ...
Страница 398: ...13 30 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 13 Configuring VLANs Configuring VMPS ...
Страница 424: ...15 18 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 15 Configuring VTP Monitoring VTP ...
Страница 628: ...26 8 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 26 Configuring UDLD Displaying UDLD Status ...
Страница 660: ...28 8 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 28 Configuring RMON Displaying RMON Status ...
Страница 888: ...38 32 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 38 Troubleshooting Troubleshooting Tables ...