Power Supply Installation Considerations
Allocation of PoE Power to Modules
The G‐Series firmware determines the power available for PoE based on hardware configuration, power supply status, and power supply redundancy mode. The system calculates and reserves the correct amount of power required by the installed IOMs and motherboard and then makes the balance of power available for PoE. When any change is made to the hardware configuration, power supply status, or redundancy mode, the firmware recalculates the power available for PoE.
The power available for PoE is distributed to each PoE‐capable base board and IOM based on the configured allocation mode:
•Automatic mode (default), in which available power is distributed evenly to PoE‐capable modules based on PoE port count. Any change in available power, due to a change in power supply status or redundancy mode or to the addition or removal of modules, will trigger an automatic redistribution of power to the PoE controller on each PoE‐capable module.
•Manual mode, in which the power budget for each PoE‐capable module is manually configured, using either CLI commands or the MIBs. The sum of the wattage configured for each module cannot exceed the total power available on the switch for PoE.
The configured wattage assignments are used to calculate each slot’s percentage of total available power. If the total available PoE power changes, a redistribution of available power will occur, applying the calculated percentages.
When manual distribution mode is configured, if a PoE module is added to the G‐Series switch, the PoE power budget for existing modules will not be recalculated. The new module will have a power budget of zero until it is manually provisioned. Since the sum of the manually provisioned wattages cannot exceed the total system power available, it may be necessary to adjust existing budgets to free up power for the new module.
When a PoE module is removed from a G‐Series switch configured with manual power distribution mode, the PoE budget for each module will not be recalculated, based on the assumption that the module removed will be replaced with a new module that should receive the same amount of PoE power.
If the power needed or requested exceeds the power available, the system will generate a trap to notify the system manager.
For more information on configuring Manual mode, see the Enterasys G‐Series CLI Reference.
Power Distribution Upon Power Supply Removal or Addition
Power Supply Removal
When a power supply is removed, the G3 responds to the decrease in available power by:
1.Detecting the power supply removal and recalculating available power.
2.Subtracting the power capacity for its base system and all installed modules from available power.
3.Distributing remaining power equally across installed PoE controllers by reprogramming maximum power in each controller.
4.Dropping support to PoE devices as necessary to stay within the programmed maximum power.
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