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Cisco 7401ASR Installation and Configuration Guide
OL-5419-01 B0
Chapter3 Starting and Configuring
Functional Overview
When you remove or insert a port adapter or service adapter in a Cisco 7401ASR router, the pins send
signals to notify the system, which then performs as follows:
1. Rapidly scans the system for configuration changes.
2. Initializes all newly inserted port adapter or service adapter, noting any removed interfaces and
placing them in the administratively shutdown state.
3. Brings all previously configured interfaces on the port adapter back to the state they were in when
they were removed. Any newly inserted interface is put in the administratively shutdown state, as if
it was present (but not configured) at boot time. If a similar port adapter ty pe is reinserted into a slot,
its ports are configured and brought online up to the port count of the original port adapter. (A
service adapter has no configurable ports.)
Environmental Monitoring and Reporting Functions
Environmental monitoring and reporting functions allow you to maintain normal system operation by
identifying and resolving adverse conditions prior to loss of operation. The environmental monito ring
functions constantly monitor the internal chassis air temperature and DC supply voltages and currents.
If conditions reach shutdown thresholds, the system shuts down to avoid equipment da mage from
excessive heat. The reporting functions periodically log the values of measured parameters so that you
can retrieve them for analysis later, and the reporting functions display warnings on the console if any
of the monitored parameters exceed defined thresholds.

Environmental Monitoring

The environmental monitoring functions use two sensors, Sensor 1 near the processor, and Sensor 2, near
the power supply. If the air temperature exceeds a defined threshold, the system controller displays
warning messages on the console terminal, and if the temperature exceeds the shutdown threshold, the
system controller shuts down the system. The system stores the present parameter measurements for both
temperature and DC voltage in NVRAM so you can retrieve them later as a report of t h e la st shutd own
parameters.
If an internal power supply temperature or voltage reaches a critical level, the power supply shuts d own
without any interaction with the system processor.
The environmental monitoring functions use the following levels of status conditions to monitor the
system:
•Normal—All monitored parameters are within normal tolerances.
•Warn ing —The system has exceeded a specified threshold. The system continues to operate, but
operator action is recommended to bring the system back to a normal state.
•Critical—An out-of-tolerance temperature or voltage condition exists. T he sy st em c on tinu es to
operate; however, the system is approaching shutdown. Immediate operator action is required.
•Shutdown—The processor has detected a temperature condition that could result in p hysical damage
to system components and has disabled DC power to all internal components. This condition
requires immediate operator action. All DC power remains disabled until you toggle the power
switch. Before any shutdown, the system logs the status of monitored parameters in NVRAM so you
can retrieve it later to help determine the cause of the problem.
•Power supply shutdown—The power supply detected an internal out-of-tolerance overvoltage,
overcurrent, or temperature condition and shut itself down. All DC power remains disabled until you
toggle the power switch.