Power Class

According to the IEEE 802.3at standard, a power class determines the amount of power a PD receives from power-sourcing equipment. When a valid PD is detected, the RUCKUS PoE device performs power classification by inducing a specific voltage and measuring the current consumption of the PD. Depending on the measured current, the appropriate class is assigned to the PD. PDs that do not support classification are assigned a class of 0.

In the IEEE 802.3af standard, the maximum power output of a port is limited to 15.4W. But some power will get lost on the Ethernet cable and therefore, the minimum power available at the PD is 13W per port.

The IEEE 802.3at standard is backward compatible with IEEE 802.3af. This standard provides up to 30W of power on each port of the power equipment. The minimum output power on each port at the PD after the cable loss is 25.5W.

The new IEEE 802.3bt standard introduced two more types of powering standards, Type 3 and Type 4, and four new classes, from Class 5 to Class 8. Type 3 can carry up to 60W for each PoE port and Type 4 can provide maximum power output of 90W per PoE port. IEEE 802.3bt is backward compatible with 802.3af and 802.3at.

The following table shows the different power classes and their respective power consumption needs.

Power Classes for PDs

Class

Power (watts) from Power-Sourcing Device

IEEE 802.3af (Standard PoE) IEEE 802.3af (PoE+) IEEE 802.3bt PoE++/LT PoE Power over HDBaseT (PoH)

0

15.4

15.4

15.4

15.4

15.4

1

4

4

4

4

4

2

7

7

7

7

7

3

15.4

15.4

15.4

15.4

15.4

4

N/A

30

30

30

Default is 60. If PoE overdrive is enabled, up to 95W is supported.

5

N/A

N/A

45

45

N/A

6

N/A

N/A

60

65 (if overdrive is enabled)

N/A

7

N/A

N/A

75

90 (if overdrive is enabled)

N/A

8

N/A

N/A

90

120 (if overdrive is enabled)

N/A

Power management is enhanced to enable the port and also power up the legacy PD or Class 1, Class 2, or Class 3 PDs even if the available power is less than 30W. In releases prior to FastIron 08.0.70, the default power reservation of 30W places the ports in the denied state when the available power is less than 30W. The port remains in the denied state even if you want to use lower-class PDs on the ports. With the new enhancement, the device monitors the denied ports every 5 seconds and at every instance, if the available power is less than 30W but has more than Class 1, 2, or 3 power, the ports are enabled and, if the PD is detected in these classes, the PD is powered up. This process continues until all denied ports are monitored for PD detection or the available power is less than 4W. The PDs will not be powered up if the available power is less than Class 1 PD power (4W).

Power Requirement for Ports and PD Detection

Available System Power Power Reservation for PD Detection
Class 8 Power 90W
> Class 7 Power (between 75W and 90W) 75W
> Class 6 Power (between 60W and 75W) 60W
> Class 5 Power (between 45W and 60W) 45W
> Class 4 Power (between 30W and 45W) 30W
> Class 3 Power (between 15.4W and 30W) 15.4W
> Class 2 Power (between 7W and 15.4W) 7W
> Class 1 Power (between 4W and 7W) 4W
< Class 1 Power (between 0W and 4W) Ports will be in disabled state (power-denied state)
The Power Supply Units (PSUs) on ICX 7550 devices are the RPS22 (PoE) and the RPS21 (non-PoE). The capacity of the RPS22 varies with the AC input voltage and the number of PSUs. The RPS21 PSU (non-PoE) is not compatible with PoE models.

The PSU AC input (110-240V) remains the same while configuring perpetual PoE and fast boot PoE. Moving the PSU AC input from 240V to 110V reduces the power supply capacity. If perpetual PoE or fast boot PoE is applied on all ports, and the connected PDs are already using more than the capacity of the PSU with 110V, then there is a possibility of PSU shutdown.

ICX 7550 Models Using AC < 180V

Model PSU Count Maximum 12V Output Power (W) Maximum PoE Output Power (W)
ICX 7550-24P 1 154W 812W
2 154W each 812W x 2
ICX 7550-48P 1 164W 812W
2 164W each 812W x 2
ICX 7550-24ZP 1 197W 815W
2 197W each 815W x 2
ICX 7550-48ZP 1 250W 763W
2 250W each 763W x 2

ICX 7550 Models Using AC > 180V

Model PSU Count Maximum 12V Output Power (W) Maximum PoE Output Power (W)
ICX 7550-24P 1 154W 950W
2 154W each 950W x 2
ICX 7550-48P 1 164W 950W
2 164W each 950W x 2
ICX 7550-24ZP 1 197W 954W
2 197W each 954W x 2
ICX 7550-48ZP 1 250W 929W
2 250W each 929W x 2

Scaling numbers depend on the PSUs and the power budget of the PDs.

Maximum Number of Ports Supported for the ICX 7550

Model VAC (V) PSU Max PoE Output Power Draw (W) Maximum Number of Ports Supported
802.3af/at/bt Class 3 802.3at/bt Class 4 PoE Overdrive 802.3bt Class 5 802.3bt Class 6 802.3bt Class 7 802.3bt Class 8 802.3bt Class 9
2-Pair 2-Pair 2-Pair 4-Pair 4-Pair 4-Pair 4-Pair 4-Pair
15.4W 30W 45W 45W 60W 70W 90W 95W
ICX 7550-24P 100-180 1 812 24 24 18 N/A N/A N/A N/A N/A
2 1624 24 24 24 N/A N/A N/A N/A N/A
181-240 1 950 24 24 21 N/A N/A N/A N/A N/A
2 1900 24 24 24 N/A N/A N/A N/A N/A
ICX 7550-48P 100-180 1 812 48 27 18 N/A N/A N/A N/A N/A
2 1624 48 48 36 N/A N/A N/A N/A N/A
181-240 1 950 48 31 21 N/A N/A N/A N/A N/A
2 1900 48 48 42 N/A N/A N/A N/A N/A
ICX 7550-24ZP 100-180 1 815 24 24 18 18 13 10 9 8
2 1630 24 24 24 24 24 21 18 17
181-240 1 954 24 24 21 21 15 12 10 10
2 1908 24 24 24 24 24 24 21 20
ICX7550-48ZP 100-180 1 753 48 25 16 16 12 10 8 8
2 1526 48 48 33 33 25 20 16 16
181-240 1 929 48 30 20 20 15 12 10 9
2 1858 48 48 41 41 30 24 20 19

PoE Overdrive

Note: PoE Overdrive is not supported on the RUCKUS ICX 8200 devices except ICX 8200-24ZP, ICX 8200-48ZP, and ICX 8200-C08ZP devices.
Note: PoE Overdrive is not supported on the RUCKUS ICX 8100 devices.

PoE overdrive is not part of the IEEE standard, but a RUCKUS proprietary enhancement. In releases prior to FastIron 08.0.61, a PD could negotiate only for a power lower than the limit defined by the power class of the PD through the LLDP-MED messages. Beginning with FastIron 08.0.61, PoE overdrive allows the Class 0 and Class 4 PDs to negotiate for power greater than the 30W allocation (refer to PoE Overdrive Limit on Different Hardware Models through PDs Allowed for POE Overdrive on PoE+ Ports for PoE overdrive support details). The maximum power that can be processed based on LLDP-MED negotiation is limited to the hardware capability of the PSE. If the PD negotiates for power more than the hardware limit, the PSE allocates only up to the hardware capability of the PSE.

PoE overdrive is disabled by default. When RUCKUS PDs negotiate for power greater than the 30W allocation on PoE+ ports that support overdrive through LLDP-MED messages, PoE overdrive is enabled automatically. When the port mode dynamically changes to overdrive mode, the power is cycled (off and on) on the port. To avoid PD reload, manually apply the inline power overdrive configuration on the port before connecting the PD. PoE overdrive is a per-port configuration and can be configured on a range of ports.

Note: PoE overdrive on PoE+ ports is available for RUCKUS PDs. Beginning with FastIron 08.0.92, PoE overdrive on PoE+ ports is available for the RUCKUS-tested third-party PDs. RUCKUS PDs use UPoE when connected to PoH ports.

If PoE overdrive is enabled on the ports dynamically (when overdrive-supported RUCKUS PDs are connected), it is disabled on the ports automatically when the PD is disconnected. This automatic overdrive configuration is not displayed in the running configuration.

By default, the initial power allocation is 60W on PoH ports and 30W on PoE+ ports. With the PoE overdrive configuration, the initial power allocation is 95W on PoH ports and 30W on PoE+ ports.

The ICX devices listed in Ports Supporting Overdrive Feature are a mix of 2-pair and 4-pair ports that support the 802.3bt standard. Automatic overdrive is used for 2-pair ports and only RUCKUS-tested third-party PDs receive more than 30W. RUCKUS PDs that require more than 30W on 2-pair ports automatically get the power without any configuration, and there is no reload of the PD.

Note: Non-RUCKUS PDs cannot take more than 30W on 2-pair ports.
The ICX 7650 cannot detect PoE Class 5 to Class 8. To avoid a PD reload, run the inline power overdrive command on the 2-pair ports only.

The ICX devices with 4-pair ports listed in Ports Supporting Overdrive Feature require the inline power overdrive command to supply more power to PoH and PoE++ PDs.

You must manually configure the inline power power-limit command on the port to support PoH and PoE++ PDs. The ICX devices listed in PoE Overdrive Limit on Different Hardware Models supply more power to PoH and PoE++ PDs by configuring the inline power overdrive command. The PoH and PoE++ PDs get power and come under Class 5 to Class 8 as classified under the 802.3bt standard. The power-supplying devices for the ICX devices listed in PoE Overdrive Limit on Different Hardware Models provide only 802.3bt standard power, irrespective of whether the connected PD is 802.3bt or LT PoE++-compliant.

The PoE overdrive allocation varies depending on the hardware models, as shown in the following table.

PoE Overdrive Limit on Different Hardware Models

ICX Platforms PoH Ports Overdrive: Maximum Power Capability PoE+ Ports Overdrive: Maximum Power Capability
ICX 7550-24P None

By default, the value is 60W, but with overdrive, it is 95W.

1 to 24

30W

Note: Only RUCKUS PDs can go up to 30W.

ICX 7550-24ZP 1 to 24 None
ICX 7550-48P None 1 to 48
ICX 7550-48ZP 1 to 48 None
ICX 7650-48P 1 to 8 9 to 48
ICX 7650-48ZP 25 to 48 1 to 24

PoE Overdrive Limit for ICX 7550

Classes Default Power Limit Overdrive Power Limit
Class 5 45 45
Class 6 60 65
Class 7 75 90
Class 8 90 120

Ports Supporting Overdrive Feature

ICX Platforms 2-pair 802.3bt Ports (Type 3) 4-pair 802.3bt Ports (Type 4)
ICX 7550-24P 1 to 24 None
ICX 7550-48P 1 to 48 None
ICX 7550-24ZP None 1 to 24
ICX 7550-48ZP None 1 to 48
ICX 7650-48P 9 to 48 1 to 8
ICX 7650-48ZP 1 to 24 25 to 48

PDs Allowed for POE Overdrive on PoE+ Ports

Supported PDs Minimum Software Release
RUCKUS R720 AP SmartZone 3.5.1
RUCKUS R730 AP SmartZone 3.6.2
RUCKUS-tested third-party PDs FastIron 08.0.92

Power Specifications

The 802.3af (PoE) standard limits power to 15.4 watts (44 to 50 volts) from the power-sourcing device, in compliance with safety standards and existing wiring limitations. Though limited by the 802.3af standard, 15.4 watts of power was ample for most PDs, which consumed an average of 5 to 12 watts of power (IP phones, wireless LAN access points, and network surveillance cameras each consume an average of 3.5 to 9 watts of power). The 802.3at 2008 (PoE+) standard nearly doubles the power, providing 30 watts (52 to 55 volts) from the power-sourcing device.

Note: By default, PoH ports on RUCKUS devices allocate 60W for Class 4 PDs. If PoE overdrive is enabled, PoH ports allocate 95W for Class 4 PDs.

The PoE power supply provides power to the PoE circuitry block and ultimately to PoE power-consuming devices. The number of PoE power-consuming devices that one PoE power supply can support depends on the number of watts required by each power-consuming device and the capacity of the power supply or power supplies. Each PoE+ port supports a maximum of 30 watts of power per power-consuming device. Each PoH port supports a maximum of 95 watts of power.

As an example, if each PoE power-consuming device attached to a RUCKUS PoE device is budgeted to consume 30 watts of power, one 720- or 748-watt power supply can power up to 24 PoE ports. RUCKUS platforms support either a second power supply or an external power supply (EPS) to augment PoE power budget, depending on the product. Refer to the power supply specifications in the RUCKUS FastIron hardware installation guide for the appropriate RUCKUS device.

Parent topic: Power over Ethernet Overview