PoE Control

1. Function Overview

PoE (Power over Ethernet) is a technology that supplies power using an Ethernet cable (category 5e or higher).
This product complies with IEEE 802.3at, which allows the product to supply power to Class 4 powered devices.
In IEEE 802.3at, terms called

  • Power supply side (device that supplies power) PSE: Power Sourcing Equipment

  • Power receiving side (device that receives power): PD: Powered Device

are defined.
This product uses Alternative A, which uses the signal lines (1, 2, 3, 6) of cables as the power supply method.

2. Definition of Terms Used

None

3. Function Details

3.1. PoE power supply function enable/disable control

Ports that support PoE power supply of this product (hereinafter referred to as PoE ports) are as follows.

  • SWX2310P-10G: ports 1 to 8

  • SWX2310P-18G: ports 1 to 16

  • SWX2310P-28GT: ports 1 to 24

This product allows you to enable/disable the power supply function for each port.
The power supply function of all the PoE ports of this product is enabled as the factory default.
If the connected device is a normal Ethernet device, the power will not be supplied and the device will operate as a normal Ethernet port.
This product continues to provide power to PDs even if the ports are shut down.

3.2. Power supply class and maximum number of ports that can be powered simultaneously

This product is a power supply device that complies with the PoE standards. It can supply up to 30 W of power per port.
It automatically detects the connected PD, identifies its power class, and starts the power supply.
The following table lists the power classes defined in IEEE 802.3at and the guideline for the maximum number of ports that can be simultaneously powered (the number of ports that can be simultaneously connected when each PD consumes power up to its limit).

Class

Power of device that receives power (MAX)

Power of device that supplies power

Maximum number of ports that can be powered simultaneously (Upper limit of PoE power supply)

SWX2310P-10G(124W)

SWX2310P-18G(247W)

SWX2310P-28GT(370W)

0

13.0 W

15.4 W

8

16

24

1

3.84 W

4.0 W

8

16

24

2

6.49 W

7.0 W

8

16

24

3

13.0 W

15.4 W

8

16

24

4

25.5 W

30.0 W

4 (*)

8 (*)

12 (*)

  • (*): Depending on the power consumption of the device that receives power, the simultaneous power supply beyond the number of ports listed can be performed.

3.3. Guard band

A guardband is a margin set for the maximum power supply to prevent unexpected power outages.
If the available power supply amount reaches or falls below the guardband, power supply to a newly connected PD will be suppressed.
For example, if the guardband is set to 10 W on the SWX2310P-10MT (upper limit of available power supply amount: 124 W), a newly-connected PD is not powered when the total PoE supply power of all ports is 114 W or more (when the available power supply amount is 10 W or less).
Setting this guard band value appropriately can prevent a newly connected PD from stopping the power supply to other PDs.
This product allows you to set the guardband value within the range of 0 to 30 W, and the value is set to 7 W as the factory default.

3.4. PoE power priority

This product allows you to specify the power supply priority order for each PoE port.
The priority is critical, high, and low in descending order, and it is set to low for all ports as the factory default.
Among ports with the same priority setting, the smaller the port number, the higher the priority. The priority goes down in the port number order (1 → 2 → 3…​).

3.5. PoE power supply actions

This product performs the following processes depending on the power consumption.

  • When the total PoE supply power of all ports is about to exceed the upper limit of the available PoE power supply
    Power supply from PoE ports is stopped in the order from the lower priority to ensure that the total PoE supply power remains within the upper limit of the available PoE power supply.
    At this time, the MODE LED status automatically transitions to the STATUS mode, and the SPEED LED of the port to which power supply has been stopped flashes orange.
    In addition, “portX.X over system power limit” is output to SYSLOG.

  • If the available power supply amount reaches or falls below the guardband
    Power will continue to be supplied to PDs that are already being powered. However, power will not be supplied to a newly-connected PD regardless of its PoE power priority.
    At this time, the MODE LED status automatically transitions to the STATUS mode, and the SPEED LED of the port to which power has not been supplied flashes orange.
    In addition, “portX.X restricted by guard band” is output to SYSLOG.

  • When the PoE supply power of a specific PoE port has exceeded the upper limit of the available PoE power supply per port
    Power supply to the corresponding PoE port will be stopped. Power supply to other PoE ports will continue.
    At this time, the MODE LED status automatically transitions to the STATUS mode, and the SPEED LED of the port to which power supply has been stopped illuminates steady orange.
    In addition, “portX.X over load” is output to SYSLOG.

  • If the PoE supply power is other than the above (within normal range)
    Power supply to PDs will continue.
    At this time, if the MODE LED status has transitioned to the STATUS mode due to the above factors, the MODE LED will return to the MODE before the automatic transition.

In addition, the following processing will be performed if the PoE port status or the available power supply amount has changed.

  • When power supply is started
    “portX.X power on” is output to SYSLOG.
    When the MODE LED is in the PoE mode, the LINK LED of the port that has started supplying power illuminates steady green.

  • When power supply is stopped
    “portX.X power off” is output to SYSLOG.
    When the MODE LED is in the PoE mode, the LINK LED of the port that has stopped supplying power switches off.

  • If the available power supply amount reaches or falls below the guardband
    “Supplying power reached to guard band threshold” is output to SYSLOG.

  • If the available power supply amount recovers from the state on or below the guardband
    “Supplying power fell below guard band threshold” is output to SYSLOG.

3.6. Power supply setting by LLDP

When the product receives an LLDP frame containing the Power via MDI TLV from a PD, it automatically changes the power supply action of the PoE port according to the received frame setting value.
This function only works on PoE ports that can receive LLDP frames.
The Power via MDI TLVs and the corresponding actions to be changed are as shown below.

Power via MDI TLV (IEEE802.3) Action to be changed

Power priority

PoE power priority

PD requested power value

Upper limit of available power supply amount per port

4. Related Commands

Related commands are indicated below.
For details on the commands, refer to the Command Reference.

Operations Operating commands

Set the PoE power supply function for the entire system

power-inline

Set the PoE power supply function on an interface basis

power-inline

Set the description text for PoE ports

power-inline description

Set the PoE port priority

power-inline priority

Set a guard band

power-inline guardband

Show PoE power supply information

show power-inline

5. Examples of Command Execution

6. PoE Port Power Supply Settings

Specify the settings for the power supply function of port1.8.

Yamaha(config)#power-inline enable (1)
Yamaha(config)#interface port1.8
Yamaha(config-if)#power-inline description "AP1" (2)
Yamaha(config-if)#power-inline priorty critical (3)
Yamaha(config-if)#power-inline enable (4)
Yamaha(config-if)#exit
Yamaha(config)#exit
1 Enable the PoE supply function for the entire system. * Not required if the default settings are used
2 Set “AP1” as the PoE port description
3 Set the priority of the PoE port to the highest (critical)
4 Enable the PoE supply function for the interface. * Not required if the default settings are used

7. Points of Caution

None

8. Related Documentation