Ruijie RG-S2900G-E Series - Page 95

Configuration Guide Configuring PoE Configuration
The following table makes a comparison between the power management modes of PoE switches:
Mode\Feature
Auto
Energy-Saving
Static
Power calculation criteria
Power classes of PDs
Current power consumption of PDs
User configurations
Whether it is the default mode
Default mode
Optional mode
Optional mode
Command
Function
Ruijie# configure
Enters the global configuration mode
Ruijie(config)# poe mode { auto | energy-saving | static }
Sets the power management mode of the PoE system to
auto, energy-saving, or static mode
By default, the auto mode is applied for power management on a switch.
For example, you can run the following commands in turn to set power management on a switch to the energy-saving mode:
Ruijie# configure
Ruijie(config)# poe mode energy-saving
 After the power management mode is changed, all PoE ports are powered off and powered up again in new power
management mode.
 If no settings for port power allocation are made on a switch that has changed to the static mode, the system will
automatically allocate power to ports. For PDs that only support 802.3af, the switch will allocate 15.4 W to each of them.
For PDs that support 802.3at, the switch will allocate 30 W to each of them.
 In energy-saving mode, when the port is powered up, the system supplies power according to the classes of the PDs.
The system may fail to power up some ports which have been powered normally. For example, the S2928G-12P device is
in energy-saving mode. Assume that there are six class4 PDs (the actual power is 29 W) and one class3 PD (the actual
power is 5 W). At first, five class4 PDs and one class3 PD are powered up. The system has the remaining power of 35 W
(185-29*5-5=35 W). Now another class 4 PD is connected. As the remaining power of the system is greater than the
class4 power, the class4 PD is powered up. In this case, if class3 PD is disconnected and then reconnected, as the
remaining power of the system is 11 W (185-29*6=11 W), it is not enough to power up a class3 PD.
Setting the Disconnection Detection Mode
A PoE switch provides a disconnection detection function to determine whether a PD is disconnected or not. It supports
two detection mode: AC mode and DC mode.
In AC mode, the PoE switch considers that the PD connected to a port is disconnected if it detects that the port impedance
is larger than a specific value and this status lasts for a certain period of time.
In DC mode, the PoE switch considers that the PD connected to a port is disconnected if it detects that the current on the
port is smaller than a specific value and this status lasts for a certain period of time.
To set the disconnection detection mode, run the following commands in the global configuration mode. You can also set
the disconnection detection mode for a specific device only.
Command
Function
Ruijie# configure
Enters the global configuration mode
Ruijie(config)# poe disconnect-mode dc
Sets the disconnection detection mode of the PoE switch
to DC