Cisco Systems XR 12406 manual Problem-Solving with Subsystems

Chapter 4 Troubleshooting the Installation

Problem-Solving with Subsystems

–All internal DC voltages are within tolerance.

If the AC power source or any of the internal DC voltages exceed allowable tolerances, the OUTPUT OK LED shuts off, or will shut off shortly after you turn on the power. Because both the RP (which uses +2.5, +3.3 and +5 VDC), and the fan tray assembly (which uses –48 VDC) are required for operation, a problem with any of the internal DC lines can prevent the system from starting up or continuing operation.

For example, if there is a problem with the –48 VDC line that supplies the fan tray, the system powers up, but will also recognize that the fans are not operating. The system will initiate a fan failure shutdown sequence, display the appropriate warning messages, and then shut down after two minutes.

If there is a problem with any of the other DC lines, the RP will not be able to initialize the system software, so the system might attempt to start up and fail during the boot sequence.

•The blower module immediately begins operating.

•The alphanumeric LED displays on the RP indicate the following:

–The left display indicates which RP software component is running.

–The right display indicates the phase of the boot process that is currently occurring.

Problem-Solving with Subsystems

The key to solving router problems is to isolate 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 attributable to a single component, it is more efficient to first isolate the problem to a subsystem rather than trying to troubleshoot each component in the system.

	Cisco XR 12406 Router Installation Guide
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