Understanding Status LEDs to Troubleshoot
Module LEDs can show you the immediate status of a module and alert you to a problem with the module or one of its ports. It is helpful to familiarize yourself with LED activity so that you can easily detect and correct a module-related problem with minimal or no system downtime.
LED Activity During Booting
When the system boots, it runs a series of tests for each module installed in the system, and the LEDs display various configurations. Refer to the tables in this section to understand normal and abnormal LED activity. For troubleshooting information, see Table 10-4.
The system's modules have two sets of status LEDs. The top set indicates generic router and module status. The bottom set indicates module-specific status, such as port status (line modules) or fan status (SRP module).
The number against the port status LED on a line module corresponds to the number of the port on the I/O module. Some line modules have more port status LEDs than the number of ports on the I/O module. In these cases, only the LEDs for the corresponding ports on the I/O modules are active.
For example, an OCx/STMx line module can pair with either an OC3-4 or an OC12/STM4 I/O module. Consequently, the line module has four port status LEDs for OC3/STM1 operation. However, only the top set of port status LEDs are active during OC12/STM4 operation.
Table 10-2 shows the functions of the module and port status LEDs.
Table 10-2 LED identification and activity descriptions
See Redundancy Status later in this chapter. If the port is configured as DTE, the LED lights when both the DCE and the clock source are available. If the port is configured as DTE, the LED goes out when either the DCE or the clock source becomes unavailable. If the port is configured as DTE, the LED lights when either the DCE or the clock source becomes unavailable. If the port is configured as DTE, the LE goes out when both the DCE and the clock source are available.
The following figures show a representative module for each of the three variations:
Note: The primary SRP module illuminates the REDUNDANT LED only when the SRP module detects that there is a secondary or standby SRP module online. The standby SRP module monitors an activity signal from the primary SRP module to determine its state; it does not shadow the operations of the primary SRP module. If the standby SRP module detects that the primary SRP module is not active, it reboots the system and takes control. (ERX-7xx/14xx models only)
LED Activity During Booting
When the system boots, it runs diagnostic tests, and the module status LEDs display various configurations. Observe the scenario presented in Table 10-3 to verify that the system has booted properly.
Note: When you reboot the system after installing a new version of the software, the line modules will appear to boot twice.
Table 10-3 Normal activity of functional status LEDS during booting
If the system detects an error during booting, the FAIL LED turns on. Some failure conditions may cause the board not to boot. In this case, the LEDs may all be off. The system should then reset the board.
If the operational software detects an error, the FAIL LED turns on. Some errors may cause a board reset. Crash information can be displayed from the console and is printed to the screen on the next reboot.
Abnormal LED Activity
See Table 10-4 to diagnose and correct problems.
Table 10-4 Troubleshooting abnormal LED activity on modules
2 Review section on proper slot group configuration in Chapter 5, Installing Modules.
You can determine the redundancy state of line modules by examining the online and redundant status LEDs (ERX-7xx/14xx models only). See Table 10-5.
Note: The REDUNDANT LED on the cOCx/STMx, FE-8, GE/FE, HSSI, and OCx/STMx modules is nonfunctional.
Table 10-5 Redundancy status of a line module