Technical information

Troubleshooting Cisco 3900 Series, 2900 Series, and 1900 Series ISRs
Problem Solving
2
Cisco 2900 and 3900 Series Hardware Installation
• Brief description of the problem
• Brief explanation of the steps you have taken to isolate the problem
Problem Solving
The key to problem solving is to isolate the problem to a specific subsystem by comparing what the
router is doing to what it should be doing.
The LEDs on the router aid you in determining router performance and operation. The LEDs are
described in the “LED Indicators” (Cisco 3900/2900, Cisco 1900).
When solving problems, consider the following router subsystems:
• Power and cooling systems—External power source, power cable, router power supply, circuit
breaker, and router fan. Also check for inadequate ventilation or air circulation.
• Interface cards—LEDs on the interface cards help identify a failure.
• Cables—External cables that connect the router to the network.
Troubleshooting the Power and Cooling Systems
Both the system LED and the fans can help you troubleshoot a power problem. Check the following
items to help isolate the problem:
Normal Indications
With the power switch on, the normal indications are:
• SYS LED on, green, and continuous
• Fan operating
Fault Indications
This is a condensed listing of LED states. For the complete listing see “LED Indicators” (Cisco
3900/2900, Cisco 1900).
Check the following symptoms to locate or eliminate faults in the power and cooling systems:
• With the power switch on, is the SYS LED on green?
– If the LED is green and continuous, the router has booted and the software is functional.
– If the LED is blinking green the system is booting or in ROM monitor mode.
– If the LED is off the system board is faulty.
– If the LED is amber, check for a system error.
• With the power switch on and the SYS LED on and green, does the fan operate?
– If no, check the fan.
– If yes, the power system is functioning.
• With the power switch on and the SYS LED off, does the fan operate?