A PD is unable to be powered on Highlighted

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This post describes the issue that a PD is unable to be powered on. Please find the way to tackle this below.


1 A PD is unable to be powered on

1.1 Introduction to PoE

 

 Definition

Power over Ethernet (PoE) provides electrical power through the Ethernet. It is also called Power over LAN (PoL) or active Ethernet.

Purpose

IP phones, network video surveillance, and wireless Ethernet networks, normally require a DC power supply.

However, access point devices are often installed outdoors or a long distance from power sockets, or it may not be practical to install the required AC/DC converter. On many large-scale LANs, administrators need to manage multiple access point devices that require uniform power supply and management. In this case, power supply management is difficult. PoE addresses this problem.

PoE is used on wired Ethernet, most commonly on LANs. PoE transmits power to terminals through data transmission lines or idle lines. PoE provides power on 10Base-T, 100Base-TX, 1000Base-T, or 2.5GE Base-T Ethernet at a distance of up to 100 m. It can be used to effectively provide centralized power for terminals such as IP phones, access points (APs), chargers of portable devices, POS machines, cameras, and data collection devices. This eliminates the need for separate cabling for power supply. PoE++ technology is a new generation of PoE power supply technology. It provides high PoE power on 2.5GE Base-T Ethernet to power high-power devices.

PoE has the following advantages:

l   It is reliable. Multiple PDs are powered by one device, facilitating power backup.

l   It is easy to deploy. Network terminals can be powered over network cables, without needing external power sources.

l   It is standardized. PoE complies with IEEE 802.3af, IEEE 802.3at, and IEEE 802.3bt, and all PoE devices use the same types of power sources.

Benefits

l   Reduces costs for power supply cables and facilitates power module installation.

l   Works with an uninterruptible power supply (UPS) to provide backup power supply for IP cameras, video servers, and IP phones.

1.2 Principles

 

 

Components in a PoE System

A PoE system consists of the following components:

l   Power-sourcing equipment (PSE): provides power to powered devices (PDs) over an Ethernet network and supports detection, analysis, and intelligent power management.

l   PD: receives power from a PSE. Examples of PDs include wireless access points (APs), portable device chargers, POS machines, and cameras. PDs are classified into standard and nonstandard PDs depending on whether they conform to IEEE standards.

l   PoE power module: provides power to a PoE system. The number of PDs connected to a PSE is limited by the power output of a PoE power module. PoE power modules are classified into built-in and external power supplies depending on whether they are pluggable.

Typical Networking

Figure 1-1 shows the typical networking of a PoE system.

Figure 1-1 Typical PoE networking

20170228165048333.png 

PoE Implementation

The process of powering PDs by a PSE has the following phases.

Figure 1-2 Process of powering PDs by a PSE

20170228164927910002.png

 

Table 1-1 PoE power supply

Phase

Overview

Description

Detection

The PSE detects whether PDs exist.

The PSE periodically transmits a low voltage with a limited current of 2.8 V to 10 V through its ports to detect PDs. If the PSE detects a DC resistance between 19 kilohms and 26.5 kilohms and capacitance that is less than or equal to 150 nF, PDs that support IEEE 802.3af, IEEE 802.3at, or IEEE 802.bt are connected to the PSE.

(Optional) Classification

The PSE classifies PDs and negotiates power supply capability with PDs.

The PSE classifies PDs and negotiates power supply capability with PDs. Two methods are available to negotiate power supply capability: The PSE obtains the power classes of PDs according to the output current; Link Layer Discovery Protocol (LLDP) is used for power capability negotiation. For details, see LLDP Power Supply Capability Negotiation.

PowerUp

The PSE starts to power PDs.

In less than 15 microseconds, the PSE provides a low voltage to PDs, which is then raised to 48 V DC.

Operation (PM&RTP)

Real-time monitoring and power management

The output voltage provided to the PDs is stabilized at 48 V DC, and the power consumption of each PD does not exceed 30 W (90 W for the S5720-14X-PWH-SI-AC).

Disconnection

The PSE detects the disconnection of PDs and stops powering the PDs.

While power is being supplied, the PSE continuously detects the input current of PDs connected to its ports. The PSE cuts off the power supply of its ports when the current of the PDs is reduced to the minimum value or increased sharply in the following situations: The PDs are removed; the power consumption of the PDs is overloaded or short-circuited; the power consumption of the PDs exceeds the power supply load. These ports enter the detection state.

 

PoE Power Supply Modes

As defined in IEEE standards, PSEs are classified into midspan and endpoint PSEs:

l   In midspan PSEs, the PoE module is installed outside of a switch, between a switch and network terminals, to power network terminals through network cables. A midspan PSE is a dedicated power management device and often deployed together with a switch. Each port number of this PSE corresponds to two RJ45 ports, one is connected to a switch through a short cable and the other connected to a remote device.

l   In endpoint PSEs, the PoE module is integrated into a switch, removing the need to deploy dedicated power cables and devices.

Huawei PoE modules are installed in endpoint PSEs. Endpoint PSEs are more widely used than midspan PSEs and are compatible with 10Base-T, 100Base-TX, 1000Base-T, and 2.5GE Base-T interfaces.

Endpoint PSEs can work in Alternative A (line pairs 1/2 and 3/6) and Alternative B (line pairs 4/5 and 7/8) power supply modes depending on the copper line pair used:

l   In Alternative A mode, power is transmitted over pairs of lines that transmit data.

The PSE provides power for PDs through line pairs 1/2 and 3/6. Pair 1/2 acts as the positive pole, and pair 3/6 acts as the negative pole. 10Base-T and 100Base-TX interfaces use line pairs 1/2 and 3/6 to transmit data, while 1000Base-T interfaces use four line pairs to transmit data. DC power and data frequency are independent. Therefore, power and data can be transmitted over a single pair of lines. In PoE and PoE+ scenarios, a PSE provides 15.4 W and 30 W power over two pairs of lines.

l   In Alternative B mode, power is transmitted over idle pairs of lines.

The PSE provides power for PDs through line pairs 4/5 and 7/8. Pair 4/5 acts as the positive pole, and pair 7/8 acts as the negative pole.

In general, standard PDs support both modes, whereas PSEs support only one mode. Huawei PSEs except S5720-14X-PWH-SI-AC support only Alternative A. The S5720-14X-PWH-SI-AC uses PoE++ for power supply and supports both Alternative A and Alternative B.

Huawei next-generation enhanced Ethernet UPoE+ switches use UPoE+ for power supply and support both Alternative A and Alternative B. 2.5G electrical interfaces support UPoE+ and provide 90 W power. Switches use four line pairs (1/2, 3/6, 4/5, and 7/8) to transmit power. Line pairs 1/2 and 3/6 provide 45 W power, and line pairs 4/5 and 7/8 also provide 45 W power.

The following table compares performance parameters of PoE, PoE+, and UPoE+.

Table 1-2 PoE parameters

Item

PoE

PoE+

UPoE+

Standards compliance

802.3af

802.3at

802.3bt

Power supply distance

100 m

100 m

100 m

Power class

0–3

0–3

0–4

Maximum current

350 mA

720 mA

960 mA

PSE output voltage

44–57 V DC

50–57 V DC

50–57 V DC

PSE output power

≤ 15.4 W

≤ 30 W

≤ 90 W

PD input voltage

36–57 V DC

42.5–57 V DC

42.5–57 V DC

Maximum PD power

12.95 W

25.5 W

81.6 W

Cable requirements

Unstructured

CAT-5 or better

CAT-5 or better

Number of power supply cable pairs

2

2

4

 

PoE Power Supply Management Modes

When the number of PDs connected to a PSE increase, the PoE power supply may be unable to provide all PDs. In this case, the PSE must manage the power supply. Power supply management is classified into two modes: automatic and manual.

l   Automatic mode: The PSE automatically powers on and off PDs according to power priorities of the interfaces connected to these PDs. You can assign critical, high, or low priority to an interface based on the importance of the PD connected to this interface. When providing power at nearly full capacity, the PSE first powers the PDs connected to interfaces with critical priority, followed by high priority. If multiple PoE interfaces have the same priority, S5720SI series PoE switches power the PDs connected to the interfaces in the sequence in which these PDs are connected to these interfaces. Other series of PoE switches power the PDs connected to the interfaces in ascending order of the interface numbers.

l   Manual mode: You can manually enable the PSE to power on and off the PDs connected to interfaces. In manual mode, the PSE ignores interface priority settings. Powering on or off the PD of a single interface does not affect the power supply status. When providing power nearly at full capacity, the PSE no longer starts providing power to newly added PDs.

LLDP Power Supply Capability Negotiation

Devices analyze the current transmitted between the PSE and PDs to classify PDs and can use LLDP to discover and advertise Media Dependent Interface (MDI) power capabilities. IEEE 802.1ab defines the optional Power via MDI Type-Length-Value (TLV). The Power via MDI TLV is encapsulated in LLDP packets, and is used for discovery and advertisement of MDI power capabilities, as well as network management. When the PSE detects a PD, the PSE and PD periodically send LLDP packets carrying the defined TLV to each other. The peer end records the information in LLDP packets for information exchange.

1.3 How to Rectify a PoE Fault

 

 

1.3.1 Confirming the Fault Symptom

When a PoE fault occurs on a switch, confirm the fault symptom. The following fault symptoms often occur:

1.         A PD is frequently powered on and off or an interface connected to a PD frequently alternates between Up and Down.

2.         A PD functions partially.

3.         A PD cannot be powered.

If the first symptom occurs, rectify the fault according to 1.3.2 The PD Is Frequently Powered On and Off.

If the second symptom occurs, rectify the fault according to 1.3.3 The PD Functions Partially.

If the third symptom occurs, rectify the fault according to 1.3.4 The PD Cannot Be Powered.

1.3.2 The PD Is Frequently Powered On and Off

If a PD is frequently powered on and off or the interface connected to a PD frequently alternates between Up and Down, check the following:

l   Whether the network cable is faulty

l   Whether the PD is not properly grounded

l   Whether the PoE power supply is unstable

Checking Whether the Network Cable Is Faulty

Confirmation Method

Use a normal network cable to reconnect the interface to this PD. If the PD can be powered, the previous network cable is faulty.

Troubleshooting Method

Replace the faulty network cable. If the fault persists, check whether the PD is properly grounded.

Checking Whether the PD Is Not Properly Grounded

Confirmation Method

If the switch is in an environment prone to electrostatic, ensure that the switch is properly grounded. Generally, switches have ground points. Check whether the yellow-green ground cable is securely connected to the ground points on the switch and rack.

Troubleshooting Method

If the switch is not properly grounded, properly ground it according to the section "Connecting the Ground Cable (on Fixed Switches)" in the Hardware Installation and Maintenance Guide - Installing Switches.

If the switch is properly grounded but the fault persists, check whether the PoE power supply is unstable.

Checking Whether the PoE Power Supply Is Unstable

IEEE 802.3at-compliant devices provide a maximum of 30 W interface output power, and IEEE 802.3af-compliant devices provide a maximum of 15.4 W interface output power. The two types of devices provide different currents to PDs and the first type provides a higher current than the second type. Some non-standard PDs support low-current power supply instead of high-current power supply. In this situation, enable the switch to support IEEE 802.3af and power PDs at a low current.

Troubleshooting Method

Log in to the switch and run the poe af-inrush enable [ slot slot-id ] command in the system view to enable the switch to support IEEE 802.3af and power PDs at a low current.

By default, a switch provides power in compliance with IEEE 802.3at.

20170228164927781003.jpg

After running the poe af-inrush enable [ slot slot-id ] command, remove and then install the non-standard PD so that it can be powered normally.

Collecting Information and Seeking Help

If you still cannot locate the fault, contact Huawei technical support personnel. For details, see Collecting Information and Seeking Help.

1.3.3 The PD Functions Partially

Troubleshooting Method

If the PD has been powered but functions partially, for example, a camera with a heating module or pan-tilt-zoom (PTZ) can provide the monitoring function normally but the heating module or PTZ rotation module cannot be powered; alternatively, an IP phone has been powered but its extended keyboard is unavailable, using the following method to rectify this fault.

If the PD has been powered but functions partially, perform the following operations to rectify this fault:

1.         Run the lldp enable command in the system view to enable LLDP globally.

2.         Run the lldp dot3-tlv power 802.3at command in the view of the interface connected to this PD to enable the interface to advertise only 802.3 Power via MDI TLV in compliance with 802.3at.

3.         Remove and then install the network cable or disable and then enable the PoE function.

Check whether the PD functions completely. If the PD still functions partially, contact Huawei technical support personnel. For details, see Collecting Information and Seeking Help.

1.3.4 The PD Cannot Be Powered

Troubleshooting Process

If the PoE function is unavailable on a switch functioning as the PSE, rectify this fault according to the following procedure.

Figure 1-3 Troubleshooting process of unavailable PoE function

20170228165240252.png 

1.         Check whether the PoE function is available on the PSE, including whether the switch supports the PoE function, whether the PoE power supply status is normal, and whether the PoE function is enabled. For details, see Checking Whether the PoE Function Is Available.

2.         Cheek whether the PSE can detect the PD. The PSE may fail to detect the PD if the network cable connecting the PSE to the PD is faulty, the PSE is not properly grounded, the PSE does not support this PD, or the PD is faulty. For details, see Checking Whether the PSE Can Detect the PD.

3.         Check whether the PSE can power this PD. including whether the power supply distance is within 100 m, the power supply management mode, whether the current time is within the power-off time range, whether the PoE power is sufficient, and whether forcible power supply is enabled. For details, see Checking Whether the PSE Can Power the PD.

Checking Whether the PoE Function Is Available

If a PoE fault occurs, first check whether the PoE function is available on the PSE.

The PoE function may be unavailable in the following situations:

l   The switch does not support the PoE function.

l   The PoE power status is abnormal.

l   The PoE function is unavailable.

Checking Whether the Switch Supports the PoE Function

Some switch models do not support the PoE function. When a PoE fault occurs, first check whether the switch supports the PoE function.

Fixed Switch

Hardware Requirements

Only the switch models with PWR or PWH in the product names support the PoE function.

Confirmation Method

l   Check the model ID of the switch. If it contains the PWR or PWH field, this switch supports the PoE function.

l   Log in to the switch and run the display device command in any view to check the product name. If the product name contains PWR or PWH, this switch supports the PoE function. For example:

<HUAWEI> display device
S5720-56C-PWR-HI-AC's Device status:                                            
Slot Sub  Type                Online    Power      Register     Status   Role
-------------------------------------------------------------------------------
0    -    S5720-56C-PWR-HI    Present   PowerOn    Registered   Normal   Master
     PWR1 POWER               Present   PowerOn    Registered   Normal   NA

Troubleshooting Method

l   If the switch does not support the PoE function, replace it with another PoE-supporting switch.

Checking the PoE Power Supply Status

A PoE switch must use required PoE power modules to provide power properly. If the power module model is incorrect or the power supply status is abnormal, a PoE fault may occur.

If the switch supports the PoE function and meets all hardware requirements, check whether the PoE power supply status is normal.

That is, perform the following operations:

l   Check whether a PoE power module is installed properly.

l   Check whether the PoE power module matches the switch model.

l   Check whether the PoE power supply status is normal.

Checking Whether a PoE Power Module Is Installed Properly

A PoE switch must have built-in or external PoE power modules installed to provide power properly.

Confirmation Method

l   If the switch is a fixed switch and uses built-in PoE power modules, no action is required. If the switch needs to have external PoE power modules installed, check whether PoE power modules are installed in power supply slots.

If many devices exist, location of this switch cannot be identified, or it is uncertain whether a power module is installed properly, log in to the switch and run the display power command in any view to check the PoE power module ID. The Online field indicates whether a power module is installed properly. For example:

<HUAWEI> display power
--------------------------------------------------------------------------
 PowerID  Online  Mode   State      Current(A)   Voltage(V)   RealPwr(W)
--------------------------------------------------------------------------
 PWR1     Present AC     Supply     4.77         53.45        253.80 
 PWR2     Present -      -          -            -            -
 PWR3     Absent  -      -          -            -            -
 PWR4     Absent  -      -          -            -            -
 POE1     Absent  -      -          -            -            -
 POE2     Absent  -      -          -            -            -
 POE3     Absent  -      -          -            -            -
 POE4     Absent  -      -          -            -            -

Troubleshooting Method

l   If the PoE power supply slot is empty, install a required PoE power module in it.

l   If the PoE power module is not installed properly, remove and then install it again. If the fault persists, check whether the power supply status is normal.

l   If a PoE power module has been installed properly but the fault persists, check whether the PoE power module matches the switch model.

Checking Whether the PoE Power Module Matches the Switch Model

Currently, fixed switches support the following external PoE power modules: 250 W AC power module, 500 W AC power module, 580 W AC power module, 650 W AC power module, 1150 W AC power module, and RPS1800 power supply (requiring 870 W AC power module).

Confirmation Method

l   According to the appearance:

           Check the nameplate of the power module. If the nameplate contains -53.5V, this power module is a PoE power module. Otherwise, this power module is a non-PoE power module.

           Non-PoE power modules (except 350 W DC power module) do not have fans, but PoE power modules have fans.

l   According to an electronic label: Check the PoE power module model of the switch. Run the display elabel command in any view to check the model of the currently used power module. For example:

<HUAWEI> display elabel
......
[Board Properties]          
BoardType=W2PSA1150         
BarCode=21021309848NF9000612
Item=02130984               
Description=AC-DC Power,-25degC-55degC,90V-290V,12V/29.2A/53.5V/15A/3.3V/100mA,5
3.5V/8.4A below 176V input  
Manufactured=2015-09-28     
VendorName=VAPEL            
IssueNumber=00              
CLEICode=                   
BOM=

Table 1-3 shows the mapping between power module types and names.

Table 1-3 Mapping between power module types and names

Type

Name

W0PSA2500

250 W AC PoE power module

W0PSA5000

500 W AC PoE power module

PAC-500WA-BE

W2PSA0580

580 W AC PoE power module

PDC-650WA-BE

650 W DC PoE power module

W2PSA1150

1150 W AC PoE power module

W2PSA0800

800 W AC power module

LE0MPSA08

W2PSD2200

2200 W DC power module

W2PSD2201

W2PSA2230

2200 W AC power module

PAC-2200WF

W0PSA2200

 

For details about the mapping between switch models and PoE power modules, see 1.5.1 Appendix 1: Mapping Between Switch Models and PoE Power Modules.

Troubleshooting Method

l   If the PoE power module does not match the switch, replace it with one that matches the switch.

l   If the fault persists after the PoE power module is replaced, check whether the PoE power supply status is normal.

Checking Whether the PoE Power Supply Status Is Normal

Confirmation Method

Run the display power command in any view to check the power supply status.

<HUAWEI> display power
------------------------------------------------------------
 Slot    PowerID  Online   Mode   State      Power(W)       
------------------------------------------------------------
 0       PWR1     Present  AC     Supply     1150.00         
 0       PWR2     Absent   -      -          -            

Table 1-4 Power supply status information

Field

Description

Value

State

Power supply working status:

l  Supply: The power module is providing power.

l  NotSupply: The power module does not provide power.

l  –: The power module is invalid or absent.

 

Troubleshooting Method

l   If the State field displays - for a PoE power module, this power module is faulty. Replace it.

l   If the fault persists after the PoE power module is replaced, check the PoE function.

Checking the PoE Function

If a PD connected to a PSE cannot be powered, check whether the PoE function has been enabled on the interface connected to this PD.

20170228164927781003.jpg

The PoE function is enabled on interfaces by default.

Checking Whether the PoE Function Is Enabled

Confirmation Method

Run the display this command on the interface connected to a PD. If this interface has the undo poe enable command configuration, the PoE function has been disabled on this interface. For example:

<HUAWEI> sysyem-view
[HUAWEI] interface GigabitEthernet0/0/6
[HUAWEI-GigabitEthernet0/0/6] display this
 port link-type access
 port default vlan 100
 

Troubleshooting Method

Run the poe enable command in the interface view to enable the PoE function on this interface again. After the PoE function has been enabled, check whether the PD can be powered. If the fault persists, check whether the PSE can detect the PD.

Checking Whether the PSE Can Detect the PD

If you confirm that the PSE is working properly but the PD still cannot be powered, check whether the PSE can detect this PD.

If the PSE cannot detect the PD, the following situations may exist:

l   The network cable connected to this PD is faulty.

l   The switch is not properly grounded.

l   The PSE does not support the PD.

l   The PD is faulty.

Checking Whether the Network Cable Connected to This PD Is Faulty

If the PD connected to an interface of the switch cannot be powered, check whether the network cable connected to this PD is faulty.

Confirmation Method

Use a normal network cable to reconnect the interface to this PD. If the PD can be powered, the previous network cable is faulty.

Troubleshooting Method

Replace the faulty network cable. If the fault persists, check whether the switch is properly grounded.

Checking Whether the Switch Is Not Properly Grounded

After a PD is connected to an interface of a switch, the switch needs to detect and classify the PD before powering it. If there is external interference, the PSE may be unable to detect, classify, and power the PD. Therefore, the PoE switch must be properly grounded.

Confirmation Method

Generally, switches have ground points. Check whether the yellow-green ground cable is securely connected to the ground points on the switch and rack.

Troubleshooting Method

If the switch is not properly grounded, properly ground it according to the section "Connecting the Ground Cable (on Fixed Switches)" in the Hardware Installation and Maintenance Guide - Installing Switches.

If the switch is properly grounded but the fault persists, check whether the PSE supports the PD.

Checking Whether the PSE Does Not Support the PD

There are PDs that do not comply with IEEE 802.3af, 802.3at, or 802.3bt. When these non-standard PDs are connected to a switch, the switch cannot detect the resistances of these PDs and cannot identify the PDs.

To enable the switch to power these PDs, enable the compatibility check function on the switch so that the switch can detect the PDs incompliant with 802.3af, 802.3at, or 802.3bt.

Confirmation Method

If non-standard PDs are connected to the switch, the switch reports non-standard PD alarms. The following is an alarm example: POE/4/NONSTANDARDPD:An invalid or non-standard PD is connected to the interface [STRING].

Troubleshooting Method

Run the poe legacy enable command on the interface connected to a non-standard PD to enable the interface to check compatibility of non-standard PDs. For example:

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet0/0/1
[HUAWEI-GigabitEthernet0/0/1] poe legacy enable

If compatibility check of non-standard PDs has been enabled on the switch, check whether the PD can be powered. If the fault persists, check whether the PD is faulty.

Checking Whether the PD Is Faulty

In a PoE system, if both the PSE and Ethernet cables are working properly but a PD is faulty, the PSE still cannot detect and power this PD.

Confirmation Method

Connect the PD suspected to be faulty to another PoE interface that can provide power normally. After a certain period, run the display poe power-state command on the PSE.

l   If Powered is displayed for the interface connected to this PD, the previous interface is faulty.

l   If the PD still cannot be powered on, this PD is faulty.

Troubleshooting Method

If the interface connected to the PD is faulty, replace the PSE. If the PD is faulty, replace it.

If the fault persists, check whether the PSE can power the PD.

Checking Whether the PSE Can Power the PD

If the PSE is working normally and can detect the PD but the PD cannot be powered, check whether the PSE can power the PD.

A PSE may be unable to power a PD in the following situations:

l   The PD is not within the maximum power supply distance of the PSE.

l   Automatic power supply management is disabled, and interfaces are not configured to power PDs.

l   The current time is within the configured PD power-off time range.

l   A power fault occurs.

Checking the PoE Power Supply Distance

Checking the Power Supply Distance

A PoE switch uses ordinary Ethernet cables to provide power, and the valid transmission distance is 100 m. Therefore, the PoE reliable power supply distance cannot exceed 100 m.

Confirmation Method

Check whether the network cable between the PSE and the PD that cannot be powered exceeds 100 m.

Troubleshooting Method

If the network cable exceeds 100 m, shorten the distance between the PSE and PD or do not use PoE for power supply.

After confirming that the PD is within the valid power supply distance of the PSE, check whether the PD can be powered. If the fault persists, check the power supply management mode and power-off time.

Checking the Power Supply Management Mode and Power-off Time Range

Checking the Power Supply Management Mode

Huawei switches support two PoE power supply management modes: automatic and manual.

l   Automatic mode: A PSE automatically powers on and off PDs according to power priorities of the interfaces connected to these PDs. Interface power priorities are critical, high, and low. When the remaining power of the PSE is insufficient to power all the connected PDs, the PSE first powers on the PDs connected to high-priority interfaces and powers off the PDs connected to low-priority interfaces.

l   Manual mode: You can manually enable the PSE to power on and off the PD connected to a specified interface. However, if the remaining system power is insufficient, it is unable to continue powering the PD.

By default, the automatic power supply management mode is used.

20170228164927781003.jpg

If the power supply management mode is manually changed to manual mode, PDs connected to interfaces must be manually powered. Otherwise, these PDs cannot be powered.

If the power supply management mode is automatic mode but a PD cannot be powered, check whether the system power is insufficient and whether the interface connected to this PD has a low priority.

Confirmation Method

Run the display poe information command in any view to check current PoE running information.

l   If the Power-Management Mode field displays manual, the current power supply management mode is manual. Manually enable the PSE to power the PD.

l   If the Power-Management Mode field displays auto, the current power supply management mode is automatic. If necessary, increase the system PoE power or change the interface power priority.

Troubleshooting Method

According to the preceding two situations, perform the following respective operations to rectify the fault:

l   In the system view, run the poe power-on interface interface-type interface-number command to manually power on the interface connected to the PD.

l   In the view of the interface connected to the PD, run the poe priority { critical | high | low } command to change the power priority of this interface.

If the PoE power supply management mode is correct but the PoE fault persists, check whether the PD power-off time range is configured.

Checking Whether the PD Power-off Time Range Is Configured

To save energy or meet some special requirements, the PoE power-off time range is configured on some interfaces of a PSE. Within this time range, the PSE automatically stops powering the PDs connected to these interfaces. When this time range expires, the PSE resumes the power supply of these PDs.

If a PD cannot be powered, check whether the PoE power-off time range is configured and whether the current time is within the configured power-off time range.

Confirmation Method

In the view of the interface connected to this PD, run the display this command to check whether this interface has the poe power-off time-range time-range-name command configuration.

For example, if the PD connected to GigabitEthernet0/0/2 cannot be powered, perform the following commands to check the interface configuration:

<HUAWEI> system-view
[HUAWEI] interface GigabitEthernet0/0/2
[HUAWEI-GigabitEthernet0/0/2] display this
#
interface GigabitEthernet0/0/2
 
#

The command output shows that a power-off time range test has been configured on this interface. If the current time is within this power-off time range, the PD connected to this interface is powered off. In the system view, run the display current-configuration | include time-range command to check the power-off time range test to determine whether the current time is within this power-off time range.

Troubleshooting Method

If the current time is within this power-off time range, run the undo poe power-off time-range command in the view of the interface connected to this PD to make this power-off time range ineffective on this interface. The time range does not take effect on the PD connected to the interface; however, the configuration of the time range is still saved in the system.

If the fault persists, check the switch power.

Checking the Switch Power

If the PSE power is insufficient, it cannot power PDs.

The PSE power is insufficient in the following situations:

l   The interface power is insufficient: If the configured maximum output power of an interface is lower than the reference power of its connected PD, this PD may fail to be powered.

l   The remaining system power is insufficient. If many PDs are connected to the PSE or the PoE power of the PSE is lower than the configured maximum output power of the interface connected to a PD, this PD may fail to be powered.

l   The reserved power percentage is high: If much PoE power is reserved, no sufficient PoE power is available to PDs and PDs cannot be powered.

Checking Whether the Interface Power Is Insufficient

If the configured maximum output power of an interface is lower than the reference power of its connected PD, this PD may fail to be powered.

Confirmation Method

Log in to the switch and run the display poe power interface interface-type interface-number command in any view to check the PoE power of the specified interface and pay attention to the following fields:

l   Port user set max power(mW): indicates the maximum output power of an interface. This field value can be configured using the poe power port-max-power command.

l   Port PD reference power(mW): indicates the reference power of the PD connected to an interface. This field value is automatically identified and analyzed by the system.

If the maximum output power of the interface is lower than the reference power of its PD, this interface cannot power this PD.

For example, if you suspect that the PD connected to GigabitEthernet0/0/2 cannot be powered because this interface does not have sufficient PoE power, run the following command for confirmation.

<HUAWEI> display poe power interface GigabitEthernet0/0/2
Port PD power(mW)           : 0
Port PD class               : 2
Port PD reference power(mW) : 
Port user set max power(mW) : 
Port PD peak power(mW)      : 0
Port PD average power(mW)   : 0

The command output shows that the maximum output power of GigabitEthernet0/0/2 is 2000 mW, lower than the reference power 7000 mW of its PD. Therefore, this PD cannot be powered.

Troubleshooting Method

If insufficient interface power leads to a PoE fault, in the specified interface view, run the undo poe power command to restore the maximum output power of this interface or run the poe power port-max-power command to specify the maximum output power of this interface to ensure that the maximum output power of this interface is higher than the reference power of its connected PD.

If the maximum output power of the interface has been higher than the reference power of its connected PD, check whether the remaining system power is insufficient.

Checking Whether the Remaining System Power Is Insufficient

If the interface power is sufficient, check whether insufficient system power leads to the failure to power the PD.

Confirmation Method

Log in to the switch and run the display poe information command in any view to check the following fields:

l   Available Total Power(mW): indicates the total available power.

l   Total Power Consumption(mW): indicates the total consumed power.

For example:

<HUAWEI> display poe information
PSE Information of slot 0:
    User Set Max Power(mW)     : 739200
    PoE Power Supply(mW)       : 369600
    Available Total Power(mW)  : 
    Total Power Consumption(mW): 
    Power Peak Value(mW)       : 0
    Power-Management Mode      : auto
    Power High Inrush          : disable 
    Port Index Priority        : enable

The command output shows that the total available power is 369600 mW and the total consumed power is 8000 mW.

The remaining system power equals the total available power minus the total consumed power. If the remaining system power is lower than the reference power of the PD that cannot be powered, the following situations exist:

1.         The configured maximum output power of the switch is lower than the reference power of this PD.

2.         The maximum output power that the switch can provide is lower than the reference power of this PD.

Troubleshooting Method

According to the preceding two situations, perform the following respective operations to rectify the fault:

1.         Log in to the switch and run the poe max-power max-power [ slot slot-id ] command in the system view to adjust the maximum system output power to be higher than the reference power of the PD.

2.         If the maximum output power that the switch can provide is insufficient for the PD, replace the switch or replace existing PoE power modules with high-power ones. In some situations, you can also replace the PD with a low-power one.

If the remaining system power is sufficient, but the PoE fault persists, check whether the reserved power percentage is high.

Checking Whether the Reserved Power Percentage Is High

Power consumption of a PD keeps changing during operation and sometimes increases sharply. As a result, the remaining system power is insufficient to support the surge in power. Before the system software determines to power off the PDs connected to low-priority interfaces, the PoE power supply will enter the overcurrent protection state because of the overload and cut off power supply to all the connected PDs. You can set the system reserved power to cope with the surge in power when power consumption increases sharply. Subsequently, the software system has time to power off the PDs connected to low-priority interfaces to ensure stable operation of other PDs.

Confirmation Method

1.         Log in to the switch and run the display poe-power command in any view to check the following fields:

           Total Available PoE Power(mW): indicates the total available PoE power.

           Reserved PoE Power Percent: indicates the reserved PoE power percentage. The default value is 20%.

2.         Run the display poe information command in any view to check the total consumed power indicated by the Total Power Consumption(mW) field.

After obtaining the total system PoE power, reserved power percentage, and total consumed power, pay attention to the following situations:

1.         If the reserved power percentage is nearly 100%, excessive PoE power is reserved and the remaining available PoE power is insufficient to PDs.

2.         After the reserved power and consumed power are subtracted from the total PoE power, the remaining power is lower than the reference power of the PD.

3.         After the reserved power and consumed power are subtracted from the total PoE power, the remaining power is higher than the reference power of the PD.

Troubleshooting Method

According to the preceding three situations, perform the following respective operations to rectify the PoE fault:

1.         Run the poe power-reserved power-reserved [ slot slot-id ] command in the system view to reduce the reserved power percentage.

2.         Run the poe power-reserved power-reserved [ slot slot-id ] command in the system view to reduce the reserved power percentage and increase the total available system power.

3.         Collect necessary information and contact Huawei technical support personnel.

If the switch power is sufficient but the PoE fault persists, try to forcibly power the PD.

Trying to Forcibly Power the PD

If the PD cannot be powered when the system power is sufficient, you are advised to run the poe force-power command in the interface view to forcibly power the PD connected to this interface.

If the fault persists, collect necessary information and contact Huawei technical support personnel.

Collecting Information and Seeking Help

If you still cannot locate the fault, contact Huawei technical support personnel.

Collecting Information

Before seeking help, collect the following information for fault location.

l   Output of the following commands

Table 1-5 Information collection commands

Command

Function

display device

Displays the component type and status.

display version

Displays the device version.

display poe power

Displays interface power information.

display poe-power

Displays PoE power information.

display poe power-state

Displays the PoE power supply status.

display poe information

Displays PoE running information on the device.

 

l   Brief description of the fault symptom

l   Relevant alarms and logs

l   Preliminary troubleshooting results (including information about the power module model, network cable, ground point)

Seeking Help

Huawei Technical Support Website

Log in to the Huawei technical support website http://support.huawei.com/enterprise:

l   Search troubleshooting cases to find a way to fix your problem.

l   Post your questions on BBS and wait for answers from online technical experts.

Huawei Global Service Hotline and Email Address

If the fault cannot be rectified, log in to http://e.huawei.com/cn/service-hotline to obtain the Huawei global service hotline or Email address.

1.4 Cases

 

 

1.4.1 An Interface Frequently Alternates Between Up and Down When an S5700EI Powers an AP Through This Interface

Background

An S5700EI functions as a PSE to power APs. Due to onsite environment restrictions, the switch is not installed in the rack but on the ground carpet and is connected to an AP using a network cable.

Symptom

The interface connected to the AP frequently alternates between Up and Down.

Procedure

This fault indicates that the PD is frequently powered on and off. Possible causes of this fault are as follows:

l   The network cable connecting the interface to this AP is faulty.

l   The AP is not properly grounded.

l   The PoE power supply is unstable.

Step 1: Check whether the network cable connecting the interface to this AP is faulty.

Use a normal network cable to reconnect the interface to this AP. If the fault persists, the previous network cable is working normally.

Step 2: Check whether the AP is not properly grounded.

The switch is placed on the ground carpet and not properly grounded, so it is easy to produce a large electrostatic interference, affecting AP detection and classification and leading to a failure to power the AP. This is suspected as the cause of this fault.

Step 3: Properly ground the switch and then check whether the interface status and AP status becomes normal.

Step 4: Check whether the switch can power the AP normally, finding that the AP is working properly. This PoE fault has been rectified.

Summary

After a PD is connected to an interface of a switch, the switch needs to detect and classify the PD before powering it. If there is external interference, the PSE may be unable to detect, classify, and power the PD. Therefore, securely ground the switch.

1.4.2 A Switch Cannot Power a Non-Standard PD

Background

A Huawei switch functions as a PSE to power PDs. After a PD is connected to this switch, the PD cannot be powered.

Symptom

The PD cannot be powered.

Procedure

This fault indicates that the PD cannot be powered. Perform the following operations to rectify this fault:

1.         Check whether the PoE function is available on the switch, including whether the switch supports the PoE function, whether the PoE power supply status is normal, and whether the PoE function is enabled.

2.         Cheek whether the PSE can detect the PD. The PSE may fail to detect the PD if the network cable connecting the PSE to the PD is faulty, the PSE is not properly grounded, the PSE does not support this PD, or the PD is faulty.

3.         Check whether the PSE can power this PD, including whether the power supply distance is within 100 m, the power supply management mode, whether the current time is within the power-off time range, whether the PoE power is sufficient, and whether forcible power supply is enabled.

Step 1: Check whether the PoE function is available on the switch.

1.         The switch model is S2700-9TP-PWR-EI uses built-in PoE power modules. Ensure that the switch supports the PoE function and its power supply status is normal.

2.         In the view of GigabitEthernet0/0/6 connected to the PD, check whether the PoE function is disabled. Actually, the PoE function has been enabled on this interface.

<HUAWEI> sysyem-view
[HUAWEI] interface GigabitEthernet0/0/6
[HUAWEI-GigabitEthernet0/0/6] display this
 port link-type access
 port default vlan 100

Step 2: Cheek whether the PSE can detect this PD.

1.         Check whether the network cable connected to this PD is faulty. Use a normal network cable to reconnect the interface to this PD. If the fault persists, the previous network cable is working normally.

2.         Check whether the PD is not properly grounded. Check the ground point of the switch, finding that it has been properly grounded using a yellow-green ground cable.

3.         Check whether the PSE does not support the PD. Check alarm information on the switch, finding that it reports non-standard PD alarms: POE/4/NONSTANDARDPD:An invalid or non-standard PD is connected to the interface [gigabitEthernet0/0/6].

Step 3: Enable the PSE to check compatibility of the PD.

In the view of the interface connected to the non-standard PD, run the poe legacy enable command to enable this interface to check compatibility of non-standard PDs. For example:

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet0/0/6
[HUAWEI-GigabitEthernet0/0/6] poe legacy enable

Step 4: Check whether the PSE can power the PD normally, finding that the PD is working normally. This PoE fault has been rectified.

Summary

There are PDs that do not comply with IEEE 802.3af, 802.3at, or 802.3bt. When these non-standard PDs are connected to a switch, the switch cannot detect the resistances of these PDs and cannot identify the PDs.

To enable the switch to power these PDs, enable the compatibility check function on the switch so that the switch can detect the PDs incompliant with 802.3af, 802.3at, or 802.3bt.

 

                                   For more information,click    ★★★Summary★★★ All About Huawei Switch Features and Configurations



 

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user_2790689
Created Feb 28, 2017 09:54:21 Helpful(0) Helpful(0)

thank you for share
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paradise1680
Admin Created Mar 3, 2017 02:06:46 Helpful(0) Helpful(0)

Thank you It is very useful:)
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