Configuring Power over Ethernet Support

This chapter describes how to configure power over Ethernet (PoE) support on the Catalyst 6500 series switches.

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

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This chapter consists of these sections:

•Understanding PoE

•Configuring PoE Support

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

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/release/notes/ol_14271.html

Understanding PoE

These sections describe PoE:

•Device Roles

•PoE Overview

•CPD-Based PoE Management

•Inline Power IEEE Power Classification Override

•LLDP Inline Power Negotiation for PoE+ (IEEE 802.3at)

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 802.3at standard, shown in Cisco Feature Navigator as "PoE Plus (PoE+, PoEP) support".

–Supported only with the PoE daughtercard on the WS-X6148E-GE-45AT switching module.

–With Release 12.2(33)SXJ2 and later releases, these features are supported for IEEE 802.3at-compliant class 4 PDs:

·  Class 4: 30.00 W at the PSE (12.95 W to 25.50 W at the PD).

·  Optionally, LLDP Inline Power Negotiation for PoE+.

–With releases earlier than Release 12.2(33)SXJ2, maximum 16.8 W at the PSE (ePoE for 45 ports maximum).

•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.

–With Release 12.2(33)SXH2 and later releases, maximum 16.80 W at the PSE.

–With releases earlier than Release 12.2(33)SXH2, maximum 15.40 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.

With the WS-F6K-48-AF PoE daughtercard or the PoE daughtercard on the WS-X6148E-GE-45AT switching module, Release 12.2(33)SXH and later releases 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.

LLDP Inline Power Negotiation for PoE+ (IEEE 802.3at)

With the PoE daughtercard on the WS-X6148E-GE-45AT switching module, Release 12.2(33)SXJ2 and later releases support IEEE 802.3at-compliant LLDP PoE power negotiation, which supports additional negotiation that can reduce power usage.

Note•Enabled by default.

•The LLDP TLV used is DTE Power-via-MDI TLV.

•When a PD that performs power negotiation using multiple protocols (CDP and LLDP 802.3at) is connected to a switch, the switch locks to the first protocol packet (CDP or LLDP) that contains the power negotiation TLV. If you need to use any single protocol for power negotiation each time, you must administratively disable the other power negotiation protocols on the switch interface.

•See this publication for other the Link Layer Discovery Protocol (LLDP) configuration procedures:

http://www.cisco.com/en/US/docs/ios/cether/configuration/guide/ce_lldp-med.html

Configuring PoE Support

•Displaying PoE Status

•Configuring Per-Port PoE Support

•Configuring PoE Power Priority

•Configuring PoE Monitoring and Policing

•Disabling LLDP Power Negotiation (IEEE 802.3at)

Note The switch supports PoE only on Layer 2 switchports.

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:

–In Cisco IOS Release 12.2(33)SXH2 and later releases, the configurable range of maximum power using the max keyword is 4000 to 16800 milliwatts. For earlier releases, the configurable range for maximum power is 4000 to 15400 milliwatts. For all releases, 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.

–In Cisco IOS Release 12.2(33)SXH2 and later releases, 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. For earlier releases, the inline-powered device can negotiate a power level up to 15400 milliwatts or the configured maximum power level, if lower.

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 

 
   
 
    
   
 
    
 
   
 
    
   
 For Release 12.2(33)SXJ2 and later releases, this example shows how to verify the inline power configuration on GigabitEthernet port 2/10: 
 
    
   
 
    
Router# show power inline gigabitethernet 2/10 

 
   
 
    
   
 
    
Interface Admin  Priority     Oper      Power(Watts)    Device             Class

 
   
 
    
   
 
    
                 (enabled )            From PS To PD

 
   
 
    
   
 
    
---------------- ---------- ---------- ------- ------- ------------------- -----

 
   
 
    
   
 
    
 
   
 
    
   
 
    
Gi2/10    auto   low        on            14.5    13.1 Cisco IP Phone 9971     4

 
   
 
    
   
 
    
 
   
 
    
   
 
    
Interface AdminPowerMax Police ActConsumption

 
   
 
    
   
 
    
             (Watts)

 
   
 
    
   
 
    
--------- ------------- ------ --------------

 
   
 
    
   
 
    
 
   
 
    
   
 
    
Gi2/10             30.0 on                6.7

 
   
 
    
   
 
    
 
   
 
    
   
 For releases earlier than Release 12.2(33)SXJ2, 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 Power Priority 
 
    
   
 With Release 12.2(33)SXJ2 and later releases, you can configure how the switch responds if a power shortage occurs by setting the priority of ports providing PoE. The priority determines the order in which PoE is removed from ports if a power shortage occurs: low-priority, then high-priority, with power maintained for critical-priority ports as long as possible. These sections describe how to configure PoE power priority: 
 
    
   
 •Setting the PoE Power Priority Global Enable State 
 
    
   
 •Configuring PoE Port Power Priority 
 
     
    
    
   
 Setting the PoE Power Priority Global Enable State 
 
    
   
 To disable PoE power priority globally, perform this task: 
 
    
   
 
 
   
 
    
 
      
      
      
 
         
        
        

          Command 
        
 		 
        
        

          Purpose 
        
 		 
      
 
      
 
       
 Step 1  
 		 
       
Router(config)# no power inline priority enable 
 
       
 Disables PoE power priority globally (default: enabled). 
 		 
      
 
      
 
       
 Step 2  
 		 
       
Router# show power inline 
 
       
 Verifies the configuration. 
 		 
      
 
      
    
 
   
 
   
 
 
    
   
 This example shows how to disable PoE power priority globally: 
 
    
   
 
    
Router(config)# no power inline priority enable 

 
   
 
    
   
 
    
 
   
 
    
   
 The column heading of any show power inline command displays the PoE power priority global state ("disabled" in this example): 
 
    
   
 
    
Router# show power inline 

 
   
 
    
   
 
    
Interface Admin  Priority     Oper      Power(Watts)    Device             Class

 
   
 
    
   
 
    
                 (disabled)            From PS To PD

 
   
 
    
   
 
    
---------------- ---------- ---------- ------- ------- ------------------- -----

 
   
 
    
   
 
    
... 

 
   
 
     
    
    
   
 Configuring PoE Port Power Priority 
 
    
   
 To configure PoE port power priority, perform this task: 
 
    
   
 
 
   
 
    
 
      
      
      
 
         
        
        

          Command 
        
 		 
        
        

          Purpose 
        
 		 
      
 
      
 
       
 Step 1  
 		 
       
Router(config-if)# power inline auto priority {critical | high | low} 
 
       
 Enables PoE port power priority (default: low priority when power priority is enabled globally). 
 
 If a power shortage occurs, PoE is removed from ports in the following order: 
 
 •Low priority ports 
 
 •High priority ports 
 
 PoE is maintained for critical priority ports as long as possible. 
 		 
      
 
      
 
       
 Step 2  
 		 
       
Router# show power inline type slot/port [detail] 
 
       
 Verifies the configuration. 
 		 
      
 
      
    
 
   
 
   
 
 
    
   
 This example shows how to configure the PoE port power priority of GigabitEthernet port 2/10 as high: 
 
    
   
 
    
Router# configure terminal 

 
   
 
    
   
 
    
Router(config)# interface gigabitethernet 2/10 

 
   
 
    
   
 
    
Router(config-if)# power inline auto priority high 

 
   
 
    
   
 
    
 
   
 
    
   
 This example shows how to verify the PoE port power priority configuration of GigabitEthernet port 2/10: 
 
    
   
 
    
Router# show power inline gigabitethernet 2/10 detail | include Priority 

 
   
 
    
   
 
    
  Priority: high 

 
   
 
     
    
    
   
 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#

 
   
 
     
    
    
    
   
 Disabling LLDP Power Negotiation (IEEE 802.3at) 
 
    
   
 With the WS-X6148E-GE-45AT switching module and Release 12.2(33)SXJ2 and later releases, LLDP power negotiation is enabled by default. To disable LLDP power negotiation, perform this task: 
 
    
   
 
 
   
 
    
 
      
      
      
 
        
        

          Command 
        
 		 
        
        

          Purpose 
        
 		 
      
 
      
 
        
        
 
         
Router(config-if)# no lldp tlv-select power-management 

 
        
 
       
 Disables LLDP power negotiation (default: enabled). 
 		 
      
 
      
    
 
   
 
   
 
 
    
   
 This example shows how to display the LLDP power negotiation configuration on interface GigabitEthernet 3/1 when LLDP power negotiation is enabled: 
 
    
   
 
    
Router# show power inline gigabitethernet 2/10 detail | begin LLDP 

 
   
 
    
   
 
    
 LLDP Power Classification    -- Sent to PD --  -- Rcvd from PD --

 
   
 
    
   
 
    
   Power Type :               type 2 PSE        type 2 PD 

 
   
 
    
   
 
    
   Power Source :             primary           PSE 

 
   
 
    
   
 
    
   Power Priority :           low               high 

 
   
 
    
   
 
    
   Requested Power (watts):   11.2              11.2 

 
   
 
    
   
 
    
   Allocated Power (watts):   11.2              11.2 

 
   
 
    
   
 
    
   Power class :              4                 4 

 
   
 
    
   
 
    
 
   
 
    
   
 
    
 LLDP Legacy MDI TLV          -- Rcvd from PD --

 
   
 
    
   
 
    
   MDI power support :        0 

 
   
 
    
   
 
    
   pse power pair :           0 

 
   
 
    
   
 
    
   MDI power class :          0 

 
   
 
    
   
 
    
 
   
 
    
   
 This example shows how to disable LLDP power negotiation on interface GigabitEthernet 2/10: 
 
    
   
 
    
Router# configure terminal 

 
   
 
    
   
 
    
Enter configuration commands, one per line.  End with CNTL/Z.

 
   
 
    
   
 
    
Router(config)# interface gigabitethernet 2/10 

 
   
 
    
   
 
    
Router(config-if)# no lldp tlv-select power-management 

 
   
 
    
   
 
    
 
   
 
   
 
     
   
 
   
 
    
   
 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 
 
    
   
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