Cisco 7200 VXR router User Manual page 160

Troubleshooting Overview
Problem Solving Using a Subsystems Approach
The key to solving problems with the system is isolating the problem to a specific
subsystem. The first step in solving startup problems is to compare what the system is doing
to what it should be doing. Because a startup problem is usually caused by a single
component, it is more efficient to first isolate the problem to a subsystem rather than
troubleshoot each component in the system. For these troubleshooting procedures, consider
the following subsystems:
•
Power subsystem—This subsystem comprises the power supplies, the external power
cable, and the midplane.
•
Cooling subsystem—The chassis fan tray is the single component in this subsystem.
The fans should be operating whenever system power is on. Replace the fan tray if you
determine a fan is not functioning properly.
•
Processor subsystem—This subsystem includes the I/O controller, network processing
engine, and all port or service adapters. The system memory and management functions
reside on the I/O controller and the network processing engine, and the enabled LED on
each port adapter indicates if the port adapter is initialized. A port adapter that is
partially installed in the midplane can cause the system to hang and crash.
The following sections help you isolate a problem to one of these subsystems and direct
you to the appropriate troubleshooting section.
Identifying Startup Problems
Startup problems are commonly due to the source power or to a board (network processing
engine, I/O controller, or port or service adapter) that is dislodged from the midplane.
Although an overtemperature condition is unlikely at initial startup, the environmental
monitoring functions are included in this appendix because they also monitor internal
voltages.
When you start up the router for the first time, you should observe the startup sequence
described in the section "Starting the System and Observing Initial Conditions" in the
chapter "Observing System Startup and Performing a Basic Configuration." This section
contains a more detailed description of the normal startup sequence and describes the steps
to take if the system does not perform that sequence as expected.
A-4 Cisco 7200 VXR Installation and Configuration Guide