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 Task List 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. 1-4

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

When configuring PoE, go to these sections for information you are interested in:

l           PoE Overview

l           PoE Configuration Task List

l           Configuring the PoE Interface

l           Configuring PD Power Management

l           Configuring a Power Alarm Threshold for the PSE

l           Upgrading PSE Processing Software Online

l           Configuring a PD Disconnection Detection Mode

l           Enabling the PSE to Detect Nonstandard PDs

l           Displaying and Maintaining PoE

l           PoE Configuration Example

l           Troubleshooting PoE

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, and 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, classifies them, and supplies power to them. When detecting that a PD is unplugged, the PSE stops supplying 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 units for redundancy backup.

1.1.2  Protocol Specification

The protocol specification related to PoE is IEEE 802.3af.

1.2  PoE Configuration Task List

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           Adopting the command line.

l           Configuring a PoE configuration file and applying 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 configure multiple PoE interfaces at the same time.

 

 

The PSE supplies power for a PoE interface in the following two modes:

l           For a device with only signal cables, power is supplied over signal cables.

l           For a device with spare cables and signal cables, power can be supplied over spare cables or signal cables.

 

 

1.3.1  Configuring 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 Disabled by default.
Configure the maximum power for the PoE interface	poe max-power max-power	Optional 15,400 milliwatts by default.
Configure the PoE mode for the PoE interface	poe mode signal	Optional signal (power over signal cables) by default.
Configure a description for the PD connected to the PoE interface	poe pd-description string	Optional By default, no description for the PD connected to the PoE interface is available.

 

1.3.2  Configuring PoE Interfaces Through a PoE Configuration File

A PoE configuration file is used to configure at the same time multiple PoE interfaces with the same attributes to simplify operations. This configuration method is a supplement to the 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 Disabled by default.
Configure the maximum power for the PoE interface		poe max-power max-power	Optional 15,400 milliwatts by default.
Configure the PoE mode for the PoE interface		poe mode signal	Optional signal (power over signal cables) by default.
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 (power allocated to the critical PoE interface subtracted from maximum PSE power, 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, and 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 being powered.

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 command. 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

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.

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 80% by default.

 

1.6  Upgrading PSE Processing Software Online

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

l           refresh mode

This mode enables you to update the PSE processing software without deleting it. Normally, you can upgrade the PSE processing software in the refresh mode through the command line.

l           full mode

This mode deletes the PSE processing software and reloads it. When the PSE processing software is damaged (in this case, you can execute none of PoE commands successfully), you can upgrade the PSE software processing software in full mode to restore the PSE function.

Online PSE processing software upgrade may be unexpectedly interrupted (for example, an error results in device reboot). If you fail to upgrade the PSE processing software in full mode after reboot, you can power off the device and restart it before upgrading it again. After upgrade, restart the device manually to make the original PoE configurations take effect.

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 is AC.

 

 

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 detect nonstandard PDs	poe legacy enable	Optional Disabled by default.

 

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 ]
Display the power information of a PoE interface(s)	display poe interface power [ interface-type interface-number ]
Display the information of PSE	display poe pse
Display all information of the configurations and applications of the PoE configuration file	display poe-profile [ index index | name profile-name ]
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

 

1.10  PoE Configuration Example

I. Network requirements

The device provides power supply for PDs through PoE interfaces.

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

l           GigabitEthernet 1/0/11 and GigabitEthernet 1/0/12 are connected to access point (AP) devices.

l           The power priority of GigabitEthernet 1/0/2 is critical.

l           The power of the AP device connected to GigabitEthernet 1/0/11 does not exceed 9,000 milliwatts.

II. Network diagram

Figure 1-1 Network diagram for PoE

III. Configuration procedure

# Enable PoE on GigabitEthernet 1/0/1, GigabitEthernet 1/0/2, GigabitEthernet 1/0/11, and GigabitEthernet 1/0/12.

<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 1/0/11

[Sysname-GigabitEthernet1/0/11] poe enable

[Sysname-GigabitEthernet1/0/11] quit

[Sysname] interface GigabitEthernet 1/0/12

[Sysname-GigabitEthernet1/0/12] poe enable

[Sysname-GigabitEthernet1/0/12] quit

# Set the power priority level of GigabitEthernet 1/0/2 to critical.

<Sysname> system-view

[Sysname] interface GigabitEthernet 1/0/2

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

[Sysname-GigabitEthernet1/0/2] quit

# Set the maximum power of GigabitEthernet 1/0/11 to 9,000 milliwatts.

[Sysname] interface GigabitEthernet 1/0/11

[Sysname-GigabitEthernet1/0/11] poe max-power 9000

[Sysname-GigabitEthernet1/0/11] quit

After the configuration takes effect, the IP phone and AR device are powered and can work normally.

1.11  Troubleshooting PoE

Symptom 1: Setting of 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 first case, you can solve the problem by reducing the maximum power of the PoE interface when the guaranteed remaining power of the PSE cannot be modified.

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

Symptom 2: 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 the first case, you can solve the problem by removing the original configurations of those configurations.

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

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