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M320 AC Power Supplies Description


In the AC power configuration, the router contains two to four load-sharing AC power supplies (see Figure 1), which are located at the lower rear of the chassis in slots PEM0 through PEM3 (top to bottom). The router requires a minimum of two fully functional power supplies to operate.

To provide power redundancy, you can upgrade the number of AC power supplies from two to three or from three to four. Each AC power supply provides power to all components in the router.. Three AC power supplies provide full power redundancy. If one power supply fails or is removed, the remaining power supplies instantly assume the entire electrical load.


In a router with two power supplies (no power supply redundancy), if one power supply fails or is shut down, the other power supply goes into a “check” state and does not operate even though it has not failed (this is because the router requires two power supplies to operate).

Figure 1: AC Power Supply
AC Power Supply