Table Of Contents
Troubleshooting
Understanding POST Results
Correcting Module POST Failures
Diagnosing Problems
Troubleshooting
The LEDs on the front panel of the 2900 XL switch provide troubleshooting information about the switch. They show failures in the power-on self-test (POST), port-connectivity problems, and overall switch performance. For a full description of the switch LEDs, see the "LEDs" section on page 1-7.
Note 
You can also get statistics from the browser interface, from the command-line interface (CLI), or from an SNMP workstation. See the Cisco IOS Desktop Switching Software Configuration Guide, the Cisco IOS Desktop Switching Command Reference, or the documentation that came with your SNMP application for details.
This chapter describes the following topics for troubleshooting problems:
•Understanding POST Results
•Correcting Module POST Failures
•Diagnosing Problems
Understanding POST Results
Each time the switch is powered up, eight POSTs run automatically to check the most important system components before the switch begins forwarding packets. When the switch begins its POST, the port status LEDs turn amber for 2 seconds, and then they turn green. As each test runs, the port status LEDs turn off, starting with number 1x. The port status LEDs for ports 2x to 8x each turn off in turn as the system completes a test.
When the POST completes successfully, the port status LEDs go off, indicating that the switch is operational. If a test fails, the port status LED associated with the test turns amber, and the system LED turns amber. Table 3-1 lists the eight POST tests and their associated LEDs.
Note POST failures are usually fatal. Call Cisco Systems if your switch does not pass POST.
Table 3-1 POST Test Descriptions
Switch LED
|
Component Tested
|
LED 1x
|
DRAM
|
LED 2x
|
Flash memory
|
LED 3x
|
Switch CPU
|
LED 4x
|
System board
|
LED 5x
|
CPU interface ASIC
|
LED 6x
|
Switch core ASIC
|
LED 7x
|
Ethernet controller ASIC
|
LED 8x
|
Ethernet interfaces
|
Correcting Module POST Failures
If you install modules WS-X2914-XL and WS-X2922-XL in a Catalyst 2924M XL or 2912MF XL switch, the module fails POST. This failure occurs because the expansion modules support 2048 MAC addresses, and the switch supports 8192 MAC addresses. To correct the failure, restart the switch with the module installed. After the restart, the addressing capacity of the switch is reduced to 2048 MAC addresses.
Diagnosing Problems
Common switch problems fall into the following categories:
•Poor performance
•No connectivity
•Corrupted software
Table 3-2 describes how to detect and resolve these problems.
Table 3-2 Common Problems and Their Solutions
Symptom
|
Possible Cause
|
Resolution
|
Poor Performance or Excessive Errors.
|
Autonegotiation Mismatch.
|
See the Cisco IOS Desktop Switching Software Configuration Guide for information on identifying autonegotiation mismatches.
|
| |
Cabling Distance Exceeded.
Port statistics show excessive frame check sequence (FCS), late-collision, or alignment errors.
For 100BaseTX connections:
|
See the Cisco IOS Desktop Switching Software Configuration Guide for information on displaying port statistics.
|
| |
•The distance between the port and the attached device exceeds 100 meters.
|
Reduce the cable length to within the recommended distances.
|
| |
•If the switch is attached to a repeater, the total distance between the two end stations exceeds the 100BaseT cabling guidelines.
|
See your 100BaseT repeater documentation for cabling guidelines.
|
| |
For 10BaseT connections: The distance between the port and the attached device exceeds 100 meters.
|
Reduce the cable length to within the recommended distances.
|
| |
Bad Adapter in Attached Device.
Excessive errors found in port statistics.
|
Run adapter card diagnostic utility.
|
| |
STP checking for possible loops.
|
Wait 30 seconds for LED to turn green.
|
No Connectivity.
|
Incorrect or Bad Cable.
|
|
| |
The following are indicated by no link at both ends:
|
|
| |
A crossover cable was used when a straight-through was required, or vice-versa.
|
For the correct pinouts and the proper application of crossover vs. straight-through cables, see the "Crossover and Straight-Through Cable Pinouts" section on page B-3.
|
| |
The cable is wired incorrectly.
|
Replace with a tested good cable.
|
| |
STP checking for possible loops.
|
Wait 30 seconds for LED to turn green.
|
System LED is Amber, and All Port LEDs Are Off.
|
Corrupted Software.
|
Attach a monitor to the serial port to display the switch boot loader. For more information, see the Cisco IOS Desktop Switching Software Configuration Guide.
|
Amber Expansion Slot LED.
|
Module not seated in expansion slot.
|
Tighten the thumb screws on the module front panel.
|
Unreadable Characters on the Management Console.
|
Incorrect Baud Rate.
|
Reset the emulation software to 9600 baud.
|
Feedback
