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M7i Power System Description


The router uses either AC or DC power. You can install one or two load-sharing power supplies at the bottom rear of the chassis, as shown in M7i Chassis Description. The power supplies connect to the midplane, which distributes power to router components according to their individual voltage requirements.

For full redundancy, two power supplies are required. When the power supplies are installed and operational, they automatically share the electrical load. If a power supply stops functioning for any reason, the second power supply instantly begins providing all the power the router needs for normal functioning. It can provide full power indefinitely.

An enable control signal on the output connector of each power supply ensures that the supply is fully seated into the router midplane before the supply can be turned on. The enable pin prevents a user-accessible energy hazard, so there is no interlocking mechanism. The enable pin disables the voltage at the output connector if the power supply is not turned off before removal.

Power supplies are hot-removable and hot-insertable, as described in M7i Field-Replaceable Units (FRUs). To avoid electrical injury, carefully follow the instructions in Replacing an M7i AC Power Supply and Replacing a DC Power Supply.


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, first issue the CLI request system halt command. For more information, see .

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.