Table of Contents

Chapter 1 PoE Configuration. 1-1

1.1 PoE Overview. 1-1

1.1.1 Introduction to PoE. 1-1

1.1.2 Protocol Specification. 1-2

1.2 PoE Configuration Tasks. 1-2

1.3 Configuring the PoE Interface. 1-2

1.3.1 Configuring a PoE Interface through the Command Line. 1-3

1.3.2 Configuring PoE Interfaces through a PoE Configuration File. 1-3

1.4 Configuring PD Power Management 1-5

1.5 Configuring a Power Alarm Threshold for the PSE. 1-6

1.6 Upgrading PSE Processing Software Online. 1-6

1.7 Configuring a PD Disconnection Detection Mode. 1-7

1.8 Enabling the PSE to Detect Nonstandard PDs. 1-8

1.9 Displaying and Maintaining PoE. 1-8

1.10 PoE Configuration Example. 1-9

1.11 Troubleshooting PoE. 1-10

 

Chapter 1  PoE Configuration

1.1  PoE Overview

1.1.1  Introduction to PoE

Power over Ethernet (PoE) means that power sourcing equipment (PSE) supplies power to powered devices (PD) such as IP telephone, wireless LAN access point, and web camera from Ethernet interfaces through twisted pair cables.

I. Advantages

l           Reliable: Power is supplied in a centralized way so that it is very convenient to provide a backup power supply.

l           Easy to connect: A network terminal requires only one Ethernet cable, but no external power supply.

l           Standard: In compliance with IEEE 802.3af, a globally uniform power interface is adopted.

l           Promising: It can be applied to IP telephones, wireless LAN access points, portable chargers, card readers, web cameras, and data collectors.

II. Composition

A PoE system consists of PoE power, PSE, and PD.

l           PoE power

The whole PoE system is powered by the PoE power, which includes external PoE power and internal PoE power.

 

 

l           PSE

PSE is a card or subcard. PSE manages its own PoE interfaces independently. PSE examines the Ethernet cables connected to PoE interfaces, searches for the devices that comply with the specification, classifies them, and supplies power to them. When detecting a PD is unplugged, the PSE stops supplying the power to the PD.

An Ethernet interface with the PoE capability is called PoE interface. Currently, a PoE interface can be an FE or GE interface.

l           PD

A PD is a device accepting power from the PSE. There are standard PDs and nonstandard PDs. A standard PD refers to the one that complies with IEEE 802.3af. The PD that is being powered by the PSE can be connected to other power supply unit for redundancy backup.

1.1.2  Protocol Specification

The protocol specification related to PoE is IEEE 802.3af.

1.2  PoE Configuration Tasks

Complete these tasks to configure PoE:

Task	Remarks
Configuring the PoE Interface	Required
Configuring PD Power Management	Optional
Configuring a Power Alarm Threshold for the PSE	Optional
Upgrading PSE Processing Software Online	Optional
Configuring a PD Disconnection Detection Mode	Optional
Enabling the PSE to Detect Nonstandard PDs	Optional

 

1.3  Configuring the PoE Interface

You can configure a PoE interface in either of the following two ways:

l           Adopt the command line.

l           Configure a PoE configuration file and apply the file to the specified PoE interface(s).

Usually, you can adopt the command line to configure a single PoE interface, and adopt a PoE configuration file to batch configure PoE interfaces.

 

 

The PSE applies power to a PoE interface in two modes. For a device with only signal cables, power is supplied over signal cables. An S5500-SI switch cannot provide power supply through spare cables. So you need to use an intermediate device for an S5500-SI switch to provide power supply to devices that can only be powered by spare cables.

To clearly identify the PD connected to a PoE interface, you can give a PD description.

1.3.1  Configuring a PoE Interface through the Command Line

Follow these steps to configure a PoE interface through the command line:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enter PoE interface view	interface interface-type interface-number	—
Enable PoE	poe enable	Required By default, PoE is disabled on the PoE interface.
Configure the maximum power for the PoE interface	poe max-power max-power	Optional By default, the maximum power on the PoE interface is 15,400 milliwatts.
Configure the PoE mode for the PoE interface	poe mode signal	Optional By default, the PoE mode is signal (power over signal cables).
Configure a description for the PD connected to the PoE interface	poe pd-description string	Optional

 

1.3.2  Configuring PoE Interfaces through a PoE Configuration File

A PoE configuration file is used to batch configure PoE interfaces with the same attributes to simplify operations. This configuration method is a supplement to the common command line configuration.

Commands in a PoE configuration file are called configurations.

Follow these steps to configure PoE interfaces through a PoE configuration file:

To do…		Use the command…	Remarks
Enter system view		system-view	—
Create a PoE configuration file and enter PoE configuration file view		poe-profile profile-name [ index ]	Required
Enable PoE for the PoE interface		poe enable	Required By default, PoE is disabled on a PoE interface.
Configure the maximum power for the PoE interface		poe max-power max-power	Optional By default, the maximum power on the PoE interface is 15,400 milliwatts.
Configure the PoE mode for the PoE interface		poe mode signal	Optional By default, the PoE mode is signal (power over signal cables).
Return to system view		quit	—
Apply the PoE configuration file to the PoE interface(s)	Apply the PoE configuration file to one or more PoE interfaces	apply poe-profile { index index | name profile-name } interface interface-range	Use either approach
	Apply the PoE configuration file to the current PoE interface in PoE interface view	interface interface-type interface-number
		apply poe-profile { index index | name profile-name }

 

 

1.4  Configuring PD Power Management

The power priority of a PD depends on the priority of the PoE interface. The priority levels of PoE interfaces include critical, high and low in descending order. Power supply to a PD is subject to PD power management policies.

all PSEs implement the same PD power management policies. When the PSE supplies power to a PD,

l           By default, no power will be supplied to a new PD if the PSE power is overloaded.

l           Under the control of a priority policy, the PD with a lower priority is first powered off to guarantee the power supply to the new PD with a higher priority when the PSE power is overloaded.

If the guaranteed remaining PSE power (maximum PSE power – power allocated to the critical PoE interface, regardless of whether PoE is enabled for the PoE interface) is lower than the maximum power of the PoE interface, you will fail to set the priority of the PoE interface to critical. Otherwise, you can succeed in setting the priority to critical, this PoE interface will preempt the power of other PoE interfaces with a lower priority level. In the latter case, the PoE interfaces whose power is preempted will be powered off, but their configurations will remain unchanged. When you change the priority of a PoE interface from critical to a lower level, the PDs connecting to other PoE interfaces will have an opportunity of seizing power.

I. Configuration prerequisites

Enable PoE for PoE interfaces.

II. Configuration procedure

Follow these steps to configure PD power management:

To do…		Use the command…	Remarks
Enter system view		system-view	—
Configure the power priority for a PoE interface.	Configure the power priority for the PoE interface in PoE interface view	interface interface-type interface-number	Use either approach. By default, the power priority of a PoE interface is low.
		poe priority { critical | high | low }
	Configure the power priority for the PoE interface in PoE configuration file view	poe-profile profile-name [ index ]
		poe priority { critical | high | low }
Configure a PD power management priority policy		poe pd-policy priority	Optional By default, no PD power management priority policy is configured.

 

1.5  Configuring a Power Alarm Threshold for the PSE

l           When the current power utilization of the PSE is above or below the alarm threshold for the first time, the system will send a Trap message.

l           When the PSE starts or stops supplying power to a PD, the system will send a Trap message, too.

Follow these steps to configure a power alarm threshold for the PSE:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Configure a power alarm threshold for the PSE	poe utilization-threshold utilization-threshold-value	Optional By default, the power alarm threshold for the PSE is 80%.

 

1.6  Upgrading PSE Processing Software Online

You can upgrade the PSE processing software online in either of the following modes:

l           Refresh mode

Normally, you can upgrade the PSE processing software in the Refresh mode through the command line.

l           Full mode

When an exception, such as interruption (power failure) or error, occurs during the upgrade in Refresh mode, you can upgrade the PSE processing software in Full mode.

 

 

Follow these steps to upgrade the PSE processing software online:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Upgrade the PSE processing software online	poe update { full | refresh } filename	Optional

 

1.7  Configuring a PD Disconnection Detection Mode

To detect the PD connection with PSE, PoE provides two detection modes: AC detection and DC detection. The AC detection mode is energy saving relative to the DC detection mode.

Follow these steps to configure a PD disconnection detection mode:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Configure a PD disconnection detection mode	poe disconnect { ac | dc }	Optional The default PD disconnection detection mode depends on the device model.

 

 

1.8  Enabling the PSE to Detect Nonstandard PDs

There are standard PDs and nonstandard PDs. Usually, the PSE can detect only standard PDs and supply power to them. The PSE can detect nonstandard PDs and supply power to them only after the PSE is enabled to detect nonstandard PDs.

Follow these steps to enable the PSE to detect nonstandard PDs:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enable the PSE to supply power to the detected nonstandard PDs	poe legacy enable	Optional By default, the PSE is disabled from supplying power to the detected nonstandard PDs.

 

1.9  Displaying and Maintaining PoE

To do…	Use the command…	Remarks
Display the mapping between ID, module, and slot of all PSEs.	display poe device	Available in any view
Display the power state and information of the specified PoE interface	display poe interface [ interface-type interface-number ]	Available in any view
Display the power information of a PoE interface(s)	display poe interface power [ interface-type interface-number ]	Available in any view
Display the information of PSE	display poe pse [ pse-id ]	Available in any view
Display the power state and information of PoE interfaces connected with the PSE	display poe interface [ interface-type interfece-number ]	Available in any view
Display the power of all PoE interfaces connected with the PSE	display poe interface power [ interface-type interface-number ]	Available in any view
Display all information of the configurations and applications of the PoE configuration file	display poe-profile [ index index | name profile-name ]	Available in any view
Display all information of the configurations and applications of the PoE configuration file applied to the specified PoE interface	display poe-profile interface interface-type interface-number	Available in any view

 

1.10  PoE Configuration Example

I. Network requirements

l           GigabitEthernet1/0/1 and GigabitEthernet1/0/2 are connected to IP telephones.

l           GigabitEthernet1/0/5 and GigabitEthernet1/0/6 are connected to access point (AP) devices.

l           The power priority of GigabitEthernet1/0/2 is critical.

l           The power of the AP device connected to GigabitEthernet1/0/5 does not exceed 9,000 milliwatts.

II. Network diagram

Figure 1-1 Network diagram for PoE

III. Configuration procedure

# Enable PoE on GigabitEthernet1/0/1, GigabitEthernet1/0/2, GigabitEthernet1/0/5, and GigabitEthernet1/0/6.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] poe enable

[Sysname-GigabitEthernet1/0/1]quit

[Sysname] interface gigabitethernet 1/0/2

[Sysname-GigabitEthernet1/0/2] poe enable

[Sysname-GigabitEthernet1/0/2]quit

[Sysname] interface gigabitethernet 1/0/5

[Sysname-GigabitEthernet1/0/5] poe enable

[Sysname-GigabitEthernet1/0/5]quit

[Sysname] interface gigabitethernet 1/0/6

[Sysname-GigabitEthernet1/0/6] poe enable

# Set the power priority level of GigabitEthernet1/0/2 to critical.

<Sysname> sytem view

[Sysname] interface gigabitethernet 1/0/2

[Sysname-GigabitEthernet1/0/2] poe priority critical

# Set the maximum power of GigabitEthernet1/0/5 to 9,000 milliwatts.

[Sysname] interface gigabitethernet 1/0/5

[Sysname-GigabitEthernet1/0/5] poe max-power 9000

1.11  Troubleshooting PoE

Symptom: Setting the priority of a PoE interface to critical fails.

Analysis:

l           The guaranteed remaining power of the PSE is lower than the maximum power of the PoE interface.

l           The priority of the PoE interface is already set.

Solution:

l           In the former case, you can solve the problem by increasing the maximum PSE power, or by reducing the maximum power of the PoE interface when the guaranteed remaining power of the PSE cannot be modified.

l           In the latter case, you should first remove the priority already configured.

Symptom: Applying a PoE configuration file to a PoE interface fails.

Analysis:

l           Some configurations in the PoE configuration file are already configured.

l           Some configurations in the PoE configuration file do not meet the configuration requirements of the PoE interface.

l           Another PoE configuration file is already applied to the PoE interface.

Solution:

l           In case 1, you can solve the problem by removing the original configurations of those configurations.

l           In case 2, you need to need to modify some configurations in the PoE configuration file.

l           In case 3, you need to remove the application of the undesired PoE configuration file to the PoE interface.

Symptom: Provided that parameters are valid, configuring an AC input under-voltage threshold fails.

Analysis:

The AC input under-voltage threshold is greater than or equal to the AC input over-voltage threshold.

Solution:

You can drop the AC input under-voltage threshold below the AC input over-voltage threshold.