Cisco provides the feature of power redundancy on most of high end Cisco devices like 3650 , 6500 and 4500. These devices having the option of two PSU (Power supply unit) on single chassis. But both PSU should have input and output ratings.
Power redundancy can be configure in two ways: Combined mode and Redundant mode.
This mode is useful when we are having multiple modules or when we are having POE configured on switch to supply the power to IP Phones.
In this mode . both power supply work together in order to share the load.
This mode does’t provide the actual power redundancy. But is useful when we are having multiple modules installed or when we are having configured POE to supply the power for IP Phones.
If One power supply fails Then few modules can be power down and some modules can be stay up which can be handle by single power supply unit.
Below is the command to enable the combined mode
Switch(config)# power redundancy-mode combined
In this mode , One power supply unit can handle the total required load of power. If one power supply unit fails , Then another power supply unit takes the total power load immediately without powering down any module.
But This mode is only good if we are not having much power load.
Below is the command to enable redundant mode
Switch(config)# power redundancy-mode redundant
Switch# show power inline Switch# Show power Switch# Show power redundancy-mode Switch# Show power status Switch# Show power available Switch# Show power used Switch Show power total
Below is the image of Cisco 6509 E with two power supplies
Thanks For Reading ………………..
We will highly recommend you to read the below post on POE ( Power Over Ethernet). It will give you detailed overview on power requirement as well as it will help to take the decision that which power redundancy mode will be batter for your device.