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# 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. We recommend you familiarize yourself with LED activity so that you can easily detect and correct a module-related problem with minimal or no system downtime.

## LED Identification

Most modules have two sets of status LEDs. The top set indicates basic functional status of the router or module. The bottom set indicates system status for that module, such as port status (line modules and IOAs) or fan status (SRP modules). See Figure 32 and Figure 33 for LED locations and labeling. See Table 10 for descriptions of LED activity for all modules and IOAs.

Figure 32: Typical IOA LEDs

Figure 33: SRP IOA Module LEDs

| Note: The primary SRP module illuminates the REDUNDANT LED when the SRP module is part of a redundancy group and it is up and running (or ready to take over). 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 (and high-availability mode is not enabled), it reboots the system and takes control. If high-availability mode has been enabled, automatic switchover occurs with near hitless failover.

Table 10: LED Identification and Activity Descriptions

LED Location | LED Label | LED Indicator | LED Color | OFF to ON | ON to OFF
--- | --- | --- | --- | --- | ---
All modules |  |  |  |  |
| OK | Module status | Green | Self-test passed | Failure detected
FAIL | Module status | Red | Failure detected | Diagnostic test running
ONLINE | Module status | Green | Module online | Module offline
Line module |  |  |  |  |
| REDUN | Redundancy | Green | Module is active, and a standby module is available | Module is active, and no standby module is available
SFM module |  |  |  |  |
| REDUN | Redundancy | Green | N+1 redundancy is enabled; 2 SRPs and 3 SFMs must be installed and working. When LED is lit, you can remove the module without interrupting service. | One of the five fabric slices is down or not installed. N+1 redundancy is not enabled.
SRP module |  |  |  |  |
| REDUN | Redundancy | Green | Module is the spare system controller, is up, and is ready to take the role of the online system controller. | Module is no longer acting as the spare system controller.
| PA | Power A | Green | Power is online on source A. | Power is off.
| PB | Power B | Green | Power is online on source B. | Power is off.
| FO | Fan online | Green | Fan is online. | Critical fan failure.
| FF | Fan failure | Red | Critical fan failure. | Fan is online.
|  | NOTE: You can run the show environment command to see whether a noncritical fan failure exists.
| LK | Ethernet link | Green | Ethernet link is up. | Ethernet link is down.
| AC | Ethernet activity | Green | Blinks when Ethernet traffic is on link. | No Ethernet traffic is on link.
IOAs |  | NOTE: Not all IOAs have the following LEDs.
| ALM | Port status | Yellow | The remote end of the link is experiencing loss of signal (FERF). | No FERF present, port is working correctly.
|  | Port status | Red | Port is experiencing loss of signal. | Port is working correctly; in sync.
| OK | Port status |  | Physical link is connected properly and is functioning properly. | Physical link is not connected properly and is not functioning properly.

## LED Activity

When the system boots, it runs a series of tests for each module installed in the system, and the LEDs display various configurations. See Table 11 and Table 12 to understand normal and abnormal LED activity.

| Note: When you reboot the system after installing a new version of the software, the line modules appear to boot twice.

Table 11: Normal Activity of Functional Status LEDs During Booting

OK | FAIL | ONLINE | Status Process
--- | --- | --- | ---
off | off | off | 1. Module is in the power-up restart state; the FAIL LED stays on briefly.
off | on | off | 2. Module is initializing, and diagnostic tests are running; the FAIL LED stays on briefly.
on | off | off | 3. Module passed the diagnostics; the system boots.
on | off | on | 4. Module is now up and running.

If the system detects an error during booting, the FAIL LED lights. Some failure conditions can cause the module not to boot. In this case, the LEDs might all be off. The system then resets the module.

If the operational software detects an error, the FAIL LED lights. Some errors can cause a module reset. Crash information is displayed at the console on the next reboot.

Table 12: Troubleshooting Abnormal LED Activity on Modules

Diagnostic Signs | Possible Problems | Actions
--- | --- | ---
POWER A (PA) LED is not lit POWER B (PB) LED is not lit | System is not receiving power from Power A. System is not receiving power from Power B. | Make sure Power A and Power B terminal connections are securely attached. Verify that power switches are on. Make sure connections to power sources are securely attached. If system still does not operate, contact the Juniper Networks Technical Assistance Center.
FAIL LED lights | The line module and IOA are incompatible. A hardware failure, such as a failed module. | Make sure that the line modules and IOAs are compatible; replace if necessary. If you replaced the IOA only, issue the reload slot slot_number command. If you replaced the line module or if there was a hardware failure, the system is supposed to automatically reset the module. If the condition persists, contact the Juniper Networks Technical Assistance Center.
FAN OK LED does not light FAN FAIL LED lights | Fan is not working properly or has slowed down. Fan needs replacement. | Contact the Juniper Networks Technical Assistance Center; the system must be serviced. Note: In the fan tray for the E320 router, four of the eight fans turn on immediately upon initial power-up and the other four fans turn on after a delay of 10 seconds.
LINK LED is not lit | Ethernet connection is down. | Make sure that Ethernet cables are properly connected to both the Ethernet port and the appropriate network device. If the condition persists, contact the Juniper Networks Technical Assistance Center.
ALM LED is red | System does not recognize a port connection. Cabling is not connected properly. Cable is faulty. Clocking problem exists. | Make sure that all cables are firmly plugged into the ports and the attached network device. Verify that cables are clean. Test for faulty cables. Verify clock source and configuration. Reset the system. NOTE: Problem is corrected when normal LED activity occurs.
ALM LED is yellow | Far end receive failure (FERF) exists. | Correct FERF problem. Reset the system. NOTE: Problem is corrected when normal LED activity occurs.
PA, FO, and LK LEDs on SRP module are on, but are off on LM and SFM module | Thermal protection mode has been enabled. System temperature is too high. Vents are blocked. Fans are not operating. | Look at your console for a message indicating the problem. If you have the system log set to a severity of WARNING or higher, a Warning message indicates the failure. Issue the show environment command to display the temperatures. If the temperature is too high, power down the system. Regulate temperature. Reset the system.

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