Catalyst 6500 Release 12.2SY Software Configuration Guide
Power over Ethernet
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Power over Ethernet (PoE) Support

Table Of Contents

Power over Ethernet (PoE) Support

Prerequisites for PoE

Restrictions for PoE

Information About PoE

Device Roles

PoE Overview

CPD-Based PoE Management

Inline Power IEEE Power Classification Override

How to Configure PoE Support

Displaying PoE Status

Configuring Per-Port PoE Support

Configuring PoE Monitoring and Policing


Power over Ethernet (PoE) Support


Prerequisites for PoE

Restrictions for PoE

Information About PoE

How to Configure PoE Support


NoteFor information about switching modules that support PoE, see the Release Notes for Cisco IOS Release 12.2SY publication at this URL:

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SY/release/notes/ol_20679.html

For complete syntax and usage information for the commands used in this chapter, see these publications:

http://www.cisco.com/en/US/products/ps9536/prod_command_reference_list.html



Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

Participate in the Technical Documentation Ideas forum


Prerequisites for PoE

None.

Restrictions for PoE

PoE is supported only on Layer 2 switchports.

Information About PoE

Device Roles

PoE Overview

CPD-Based PoE Management

Inline Power IEEE Power Classification Override

Device Roles

Power sourcing equipment (PSE)—A device that provides power through a twisted-pair Ethernet connection. The switch, through switching modules equipped with Power over Ethernet (PoE) daughtercards, functions in the PSE role.

Powered device (PD)—A device powered by a PSE (for example, IP phones, IP cameras, and wireless access points).


Note Not all PoE-capable devices are powered from the switch. There are two sources of local power for PoE-capable devices:

A power supply connected to the device.

A power supply through a patch panel over the Ethernet connection to the device.

When a locally powered PoE-capable device is present on a switching module port, the switching module itself cannot detect its presence. If the device supports CDP, the supervisor engine can discover a locally powered PoE-capable device through CDP messaging with the device. If a locally powered PoE-capable device loses local power, the switching module can discover and supply power to the IP phone if the inline power mode is set to auto.


PoE Overview

Cisco PoE daughtercards support one or more PoE implementation:

IEEE 802.3af standard.

Supported with the WS-F6K-48-AF PoE daughtercard and the PoE daughtercard on the WS-X6148E-GE-45AT switching module.

Maximum 16.80 W at the PSE.

The IEEE 802.3af PoE standard defines a method to sense a PD and to immediately classify the power requirement of the PD into these per port power ranges at the PSE:

·  Class 0: Up to 15.4 W (0.44-12.95 W at the PD; default classification)

·  Class 1: Up to 4 W (0.44-3.84 W at the PD)

·  Class 2: Up to 7 W (3.84-6.49 W at the PD)

·  Class 3: Up to 15.4 W (6.49-12.95 W at the PD)

Cisco prestandard inline power—10 W at the PSE.

With a PoE daughtercard installed, a switching module can automatically detect and provision a PoE-capable device that adheres to a PoE implementation supported by the PoE daughtercard. The switching module can supply power to devices supporting other PoE implementations only through manual configuration.

Only a PD connected directly to the switch port can be powered from the switch. If a second PD is daisy-chained from the PD that is connected to the switch port, the second PD cannot be powered by the switch.

Each PD requires power to be allocated from the chassis power budget. Because each PD can have unique power requirements, more devices can be supported if the system's power management software can intelligently allocate the necessary power on a per-port basis.

You can configure ports to allocate power at a level based on the following:

If a PD is detected, with auto mode configured:

Information sensed from the device

A default level

A configured maximum level

Whether or not a PD is present on the port, with static mode configured:

A default level

A configured level

CPD-Based PoE Management

When a switching module port detects an unpowered PD, the default-allocated power is provided to the port. When the correct amount of power is determined through CDP messaging with the PD, the supervisor engine reduces or increases the allocated power, up to the hardware limit of the installed PoE daughtercard.


Caution When a PD cable is plugged into a port and the power is turned on, the supervisor engine has a 4-second timeout waiting for the link to go up on the line. During those 4 seconds, if the IP phone cable is unplugged and a network device is plugged in, the network device could be damaged. We recommend that you wait at least 10 seconds between unplugging a network device and plugging in another network device.

Inline Power IEEE Power Classification Override

The IEEE 802.3af standard contains no provision for adjustment of the power allocation. 802.3af-compliant PDs that support CDP can use CDP to override the IEEE 802.3af power classification.

The WS-F6K-48-AF PoE daughtercard or the PoE daughtercard on the WS-X6148E-GE-45AT switching module support these inline power IEEE 802.3af power classification override features:

Power use measurement—The ability to accurately measure the power provided by the port to the powered device.

Power policing—The ability to monitor power usage on a port.

With power measurement and policing, you can safely override the IEEE 802.3af power classification of a device that requires a power level at the lower end of its IEEE power classification range.

PoE monitoring and policing compares the power consumption on ports with the administrative maximum value (either a configured maximum value or the port's default value). If the power consumption on a monitored port exceeds the administrative maximum value, the following actions occur:

A syslog message is issued.

The monitored port is shut down and error-disabled.

The allocated power is freed.

How to Configure PoE Support

Displaying PoE Status

Configuring Per-Port PoE Support

Configuring PoE Monitoring and Policing

Displaying PoE Status

This example shows how to display the PoE status on switch:

Router# show power auxiliary 
system auxiliary power mode = on
system auxiliary power redundancy operationally = redundant
system primary connector power limit =   7266.00 Watts (173.00 Amps @ 42V)
system auxiliary connector power limit = 10500.00 Watts (250.00 Amps @ 42V)
system primary power used =              1407.00 Watts (33.50 Amps @ 42V)
system auxiliary power used =              22.68 Watts ( 0.54 Amps @ 42V)
                        Inline         Inline-Pwr     Inline-Pwr     VDB
                        Pwr-Limit      Used-Thru-Pri  Used-Thru-Aux  Aux-Pwr
Slot Card-Type          Watts   A @42V Watts   A @42V Watts   A @42V Capable
---- ------------------ ------- ------ ------- ------ ------- ------ -------
2    WS-F6K-48-AT       1600.20 38.10    23.10  0.55    11.34  0.27  Yes
4    WS-F6K-48-AT       1600.20 38.10    23.10  0.55    11.34  0.27  Yes
---- ------------------ ------- ------ ------- ------ ------- ------ -------
Totals:                                  46.20  1.10    22.68  0.54 

Configuring Per-Port PoE Support

To configure per-port PoE support, perform this task:

 
Command
Purpose

Step 1 

Router(config-if)# power inline {auto | static | never}[max milliwatts]

Configures per-port PoE support and optionally specifies a maximum inline power level in milliwatts for the port.

Step 2 

Router# show power inline {type slot/port | module slot}[detail]

Verifies the configuration.

When configuring inline power support with the power inline command, note the following information:

To configure auto-detection of a PD and PoE auto-allocation, enter the auto keyword.

To configure auto-detection of a PD but reserve a fixed PoE allocation, enter the static keyword.

To specify the maximum power to allocate to a port, enter either the auto or static keyword followed by the max keyword and the power level in milliwatts.

When the auto keyword is entered and CDP is enabled on the port, a PD that supports CDP can negotiate a different power level.

To disable auto-detection of a PD, enter the never keyword.

With a WS-F6K-GE48-AF, WS-F6K-48-AF, or the PoE daughtercard on the WS-X6148E-GE-45AT switching module:

The configurable range of maximum power using the max keyword is 4000 to 16800 milliwatts. If no maximum power level is configured, the default maximum power is 15400 milliwatts.


Note To support a large number of inline-powered ports using power levels above 15400 milliwatts on an inline power card, we recommend using the static keyword so that the power budget is deterministic.


When the auto keyword is entered and CDP is enabled on the port, an inline-powered device that supports CDP can negotiate a power level up to 16800 milliwatts unless a lower maximum power level is configured.

This example shows how to disable inline power on GigabitEthernet port 2/10:

Router# configure terminal 
Router(config)# interface gigabitethernet 2/10 
Router(config-if)# power inline never 
 
   

This example shows how to enable inline power on GigabitEthernet port 2/10:

Router# configure terminal 
Router(config)# interface gigabitethernet 2/10 
Router(config-if)# power inline auto 
 
   

This example shows how to verify the inline power configuration on GigabitEthernet port 2/10:

Router# show power inline gigabitethernet 2/10 
Interface  Admin    Oper     Power        Device
                            (Watts)
---------- ----- ---------- ------- -------------------
Fa5/1      auto  on           6.3   cisco phone device
Router#

Configuring PoE Monitoring and Policing

With the WS-F6K-48-AF PoE daughtercard or the PoE daughtercard on the WS-X6148E-GE-45AT switching module, to configure PoE monitoring and policing, perform this task:

 
Command
Purpose

Step 1 

Router(config-if)# power inline police

Enables PoE monitoring and policing.

Step 2 

Router# show power inline {type slot/port | module slot}[detail]

Verifies the configuration.

This example shows how to enable monitoring and policing on GigabitEthernet port 1/9:

Router# configure terminal 
Router(config)# interface gigabitethernet 2/10 
Router(config-if)# power inline police 
 
   

These examples shows how to verify the power monitoring and policing configuration on GigabitEthernet port 2/10:

Router# show power inline gigabitethernet 2/10 detail | include Police 
Police: on
Router#
Router# show power inline gigabitethernet 2/10 
Interface  Admin  Oper  Power (Watts)     Device   Class
                       From PS To Device
--------  -----  ---- ------- ---------  -------  -----
Gi2/10    auto   on   17.3    15.4      Ieee PD  3    
 
   
Interface  AdminPowerMax (Watts) Police  ActualConsumption
---------  --------------------- ------  ----------------- 
 Gi2/10            15.4            on    5.7 
Router#

Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

Participate in the Technical Documentation Ideas forum