Cisco Systems WSC2960X48TDL manual Maximum Power Allocation Cutoff Power on a PoE Port

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Configuring PoE

Power over Ethernet Ports

Maximum Power Allocation (Cutoff Power) on a PoE Port

When power policing is enabled, the switch determines one of the these values as the cutoff power on the PoE port in this order:

1Manually when you set the user-defined power level that the switch budgets for the port by using the power inline consumption default wattage global or interface configuration command

2Manually when you set the user-defined power level that limits the power allowed on the port by using the power inline auto max max-wattageor the power inline static max max-wattageinterface configuration command

3Automatically when the switch sets the power usage of the device by using CDP power negotiation or by the IEEE classification and LLDP power negotiation.

Use the first or second method in the previous list to manually configure the cutoff-power value by entering the power inline consumption default wattage or the power inline [auto static max] max-wattagecommand.

If you do not manually configure the cutoff-power value, the switch automatically determines it by using CDP power negotiation or the device IEEE classification and LLDP power negotiation. If CDP or LLDP are not enabled, the default value of 30 W is applied. However without CDP or LLDP, the switch does not allow devices to consume more than 15.4 W of power because values from 15400 to 30000 mW are only allocated based on CDP or LLDP requests. If a powered device consumes more than 15.4 W without CDP or LLDP negotiation, the device might be in violation of the maximum current (Imax) limitation and might experience an Icut fault for drawing more current than the maximum. The port remains in the fault state for a time before attempting to power on again. If the port continuously draws more than 15.4 W, the cycle repeats.

Note When a powered device connected to a PoE+ port restarts and sends a CDP or LLDP packet with a power TLV, the switch locks to the power-negotiation protocol of that first packet and does not respond to power requests from the other protocol. For example, if the switch is locked to CDP, it does not provide power to devices that send LLDP requests. If CDP is disabled after the switch has locked on it, the switch does not respond to LLDP power requests and can no longer power on any accessories. In this case, you should restart the powered device.

Power Consumption Values

You can configure the initial power allocation and the maximum power allocation on a port. However, these values are only the configured values that determine when the switch should turn on or turn off power on the PoE port. The maximum power allocation is not the same as the actual power consumption of the powered device. The actual cutoff power value that the switch uses for power policing is not equal to the configured power value.

When power policing is enabled, the switch polices the power usage at the switch port, which is greater than the power consumption of the device. When you are manually set the maximum power allocation, you must consider the power loss over the cable from the switch port to the powered device. The cutoff power is the sum of the rated power consumption of the powered device and the worst-case power loss over the cable.

The actual amount of power consumed by a powered device on a PoE port is the cutoff-power value plus a calibration factor of 500 mW (0.5 W). The actual cutoff value is approximate and varies from the configured value by a percentage of the configured value. For example, if the configured cutoff power is 12 W, the actual cutoff-value is 11.4 W, which is 0.05% less than the configured value.

 

Catalyst 2960-X Switch Interface and Hardware Component Configuration Guide, Cisco IOS Release 15.0(2)EX

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Contents Americas Headquarters First Published July 10Page N T E N T S Contents Configuring Auto-MDIX41 Configuring System MTU Configuring EEE Viii Bold font Document ConventionsConvention Description Reader Alert Conventions Vertical barsElement Obtaining Documentation and Submitting a Service Request Related DocumentationXii This chapter contains the following topics Information About Using the Command-Line InterfaceCommand Modes Mode Access Method Prompt Exit Method About This Mode ConfigureQuit Ctrl-ZUsing the Help System Command or Action Purpose StepMode HelpCLI Error Messages Understanding Abbreviated CommandsNo and default Forms of Commands How to Use the CLI to Configure Features Configuration LoggingConfiguring the Command History Error Message MeaningCommand or Action Changing the Command History Buffer SizeRecalling Commands Enabling and Disabling Editing Features Disabling the Command History FeaturePrivileged Exec mode Terminal no historyEditing Commands through Keystrokes Editing Command Lines That Wrap Searching and Filtering Output of show and more Commands Access-listShow more command begin include exclude regular-expression Show more command begin include excludeCommand or Action Example OL-29034-01 Finding Feature Information Information About Configuring Interface CharacteristicsInterface Types This module contains the following topicsSwitch Ports Port-Based VLANsSwitch Virtual Interfaces Trunk PortsPower over Ethernet Ports EtherChannel Port GroupsUsing the Switch USB Ports USB Mini-Type B Console PortInterface Connections USB Type a PortsInterface Configuration Mode Connecting VLANs with the SwitchDefault Ethernet Interface Configuration FeatureDefault Setting Layer 2 or switching mode switchport command VLANs 1Interface Speed and Duplex Mode Speed and Duplex Configuration GuidelinesIeee 802.3x Flow Control How to Configure Interface Characteristics Configuring Interfaces ProcedureGigabit Ethernet port 1 on switch 1 is selected Either gigabitethernet 1/0/1Configure terminal Adding a Description for an InterfaceDescription string Show interfaces interface-id descriptionInterface range port-rangemacro Configuring a Range of InterfacesConfigure terminal Enters global configuration mode Define interface-range macroname Configuring and Using Interface Range MacrosVerifies the configuration of the interfaces in the range Interface range macro macroname Configuring Ethernet InterfacesSetting the Interface Speed and Duplex Parameters Speed 10 100 1000 auto 10 NonegotiateConfiguring Ieee 802.3x Flow Control Command or Action PurposeEnter interface configuration mode Configuring SVI Autostate ExcludeEnd Returns to privileged Exec mode Switchport autostate exclude Shutting Down and Restarting the InterfaceAn SVI line state up or down Interface vlan vlan-id gigabitethernet interface-idConfiguring the Console Media Type This configuration applies to all switches in a stackConfigure terminal Line console Media-type rj45 End Shutdown Shuts down an interfaceConfiguring the USB Inactivity Timeout Configure terminal Enters the global configuration modeMonitoring Interface Characteristics Command PurposeShow interfaces interface-id status err-disabled Show interfaces interface-id switchportClearing and Resetting Interfaces and Counters Configuration Examples for Interface Characteristics Identifying Interfaces on a Stack-Capable Switch ExamplesConfiguring a Range of Interfaces Examples Adding a Description to an Interface ExampleConfiguring the Console Media Type Example Configuring and Using Interface Range Macros ExamplesSetting Interface Speed and Duplex Mode Example Configuring the USB Inactivity Timeout Example To disable the configuration, use these commandsStandards and RFCs Standard/RFC NoneRelease Modification Cisco IOS Release 15.02EX This feature was introducedTechnical Assistance Description Link OL-29034-01 This module contains the following sections Prerequisites for Auto-MDIXRestrictions for Auto-MDIX Information about Configuring Auto-MDIX How to Configure Auto-MDIXConfiguring Auto-MDIX on an Interface Auto-MDIX on an InterfaceMonitoring Auto-MDIX Example for Configuring Auto-MDIX This example shows how to enable auto-MDIX on a portPrerequisites for Ethernet Management Ports Information about the Ethernet Management PortEthernet Management Port Direct Connection to a Switch Supported Features on the Ethernet Management PortHow to Configure the Ethernet Management Port Disabling and Enabling the Ethernet Management PortAdditional References What to Do NextBootloader commands Related TopicMIBs Document TitleOL-29034-01 Configuring LLDP, LLDP-MED, and Wired Location Service Lldp and Cisco Medianet Lldp and Cisco Switch StacksLldp Supported TLVs LLDP-MED Supported TLVs Wired Location Service Default Lldp Configuration Configuration GuidelinesConfigure terminal Lldp run Lldp run Enables Lldp globally on the switchLLDP, and enter interface configuration mode Enabling LldpConfiguring Lldp Characteristics Lldp transmit Enables the interface to send Lldp packetsLldp receive Enables the interface to receive Lldp packets Show lldp Verifies the configurationSwitchconfig# lldp holdtime Configuring LLDP-MED TLVs Command or Action Purpose StepLldp med-tlv-select End Copy running-config startup-config Lldp med-tlv-select Specifies the TLV to enableConfiguring Network-Policy TLV Configuration mode. The range is 1 toVoice voice-signalingvlan vlan-idcos Dscp dvalue none untaggedConfiguring Location TLV and Wired Location Service Show network-policy profile Verifies the configurationUse one of the following WayExit Returns to global configuration mode Information, and enter interface configuration modeUse one of the following Verifies the configuration Enters location information for an interfaceEnabling Wired Location Service on the Switch Command or Action Purpose ExampleNmsp notification interval attachment location Configuring Network-Policy TLV ExamplesNmsp enable Enables the Nmsp features on the switch Command Description Civic location OL-29034-01 Information about the MTU System MTU GuidelinesHow to Configure MTU Sizes Configuring the System MTUReload Reloads the operating system Configuration Examples for System MTUShow system mtu Verifies your settings Additional References for System MTU Configuring PoE Restrictions for PoESupported Protocols and Standards Power over Ethernet PortsInformation about PoE Powered-Device Detection and Initial Power Allocation ClassPower Management Modes Power Monitoring and Power Policing Maximum Power Allocation Cutoff Power on a PoE Port How to Configure PoE Configuring a Power Management Mode on a PoE PortNever static max max-wattage Budgeting Power for Devices Connected to a PoE PortShow power inline Budgeting Power to All PoE ports No cdp run Optional Disables CDPBudgeting Power to a Specific PoE Port Configure terminal No cdp runPower inline consumption wattage Configuring Power PolicingSpecifies the physical port to be configured, and enter Power inline police actionlog errdisable Exit Show power inline police Show errdisable recoveryConfiguration mode Power inline police actionlog errdisableDown the port and puts the port in the error-disabled state Power inline police action log-Generates a syslog messageWhile still providing power to the port Budgeting Power Example Monitoring Power StatusConfiguration Examples for Configuring PoE Information About EEE EEE OverviewHow to Configure EEE Default EEE ConfigurationEEE is disabled by default Restrictions for EEESpecifies the interface to be configured, and enter Power efficient-ethernet autoCommand Monitoring EEEThis example shows how to disable EEE for an interface Configuration Examples for Configuring EEEThis example shows how to enable EEE for an interface Feature History and Information for Configuring EEE OL-29034-01 D E PoE
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