An AC-powered router has one or two load-sharing, redundant AC power supplies. Each power supply is hot-removable and hot-insertable, as described in M7I Field-Replaceable Units (FRUs). For full redundancy, two power supplies are required. If a power supply stops functioning for any reason, the remaining power supply instantly begins providing all the power the router needs for normal functioning, and can provide full power indefinitely. For more information about AC power supplies, see M7i AC Power Supply.
To replace an AC power supply, perform the following procedures:
Before removing the AC power supply from an M7i router with only one power supply, you must power off the router. See Powering Off the M7i Router. The AC power supplies are located at the bottom rear of the chassis, as shown in M7i Chassis Description. Each AC power supply weighs approximately 12 lb (5.5 kg).
![]() | Caution: Do not leave a power supply slot empty for more than a short time while the router is operational. The power supply must remain in the chassis for proper airflow. |
To remove an AC power supply (see Figure 1):
![]() | Note: If you are not removing the power supply, but simply powering it off, wait at least 60 seconds before turning it back on. If you need to power it off again, wait for at least 60 seconds after powering it on. |
Figure 1: Removing an AC Power Supply

To install an AC power supply, follow this procedure (see Figure 2):
![]() | Note: After powering off a power supply, wait at least 60 seconds before turning it back on. After powering on a power supply, wait at least 60 seconds before turning it off. If the router is completely powered off when you power on the power supply, the Routing Engine boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power off the router again, see Powering Off the M7i Router. After a power supply is powered on, it can take up to 60 seconds for status indicators—such as the output status LED on the power supply, the command display output, and messages on the LED display on the craft interface—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds. |
Figure 2: Installing an AC Power Supply
