Chapter 4 Troubleshooting the Installation
Problem-Solving with Subsystems
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.
For troubleshooting purposes, the Cisco XR 12404 router consists of the following subsystems:
•Power subsystem—Includes the following components:
–AC-input power supplies or DC-input power entry modules (PEMs). The Cisco XR 12404 router can be configured for source AC or source DC power (you can not mix AC and DC power).
–Chassis backplane power distribution. The –48 VDC power from the power supplies is transferred to the chassis backplane, which distributes –48 VDC power to the cards in the card cages through the backplane connectors.
–DC-DC converters. Each card in the router is equipped with DC-to-DC converters. These converters are controlled by the MBus module on each card. The DC-to-DC converters take –48 VDC and convert it into the voltages required by the card circuitry.
•Processor subsystem—The processor subsystem includes the RP and all line cards. The RP downloads a copy of the Cisco IOS XR image to each line card processor. The system uses alphanumeric LED displays to display status and error messages, which can help in troubleshooting.
•Cooling subsystem—The cooling subsystem is comprised of one fan tray assembly and one air filter. The fan tray assembly and air filter are
hot swappable, and can be replaced while the system is running.
Caution Replace the fan tray assembly within 2 minutes of removing it from the chassis or the router will go into a critical failure mode and shutdown due to an overtemp condition.
| | Cisco XR 12404 Router Installation Guide | | |
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| OL-13830-02 | | | 4-5 |
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