# Understanding Status LEDs to Troubleshoot

Module LEDs can show you the current 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

The system's modules have two sets of status LEDs. The top set indicates overall router and module status. The bottom set indicates module-specific status, such as port status (line modules) or fan status (SRP module).

The number next to 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 is active during OC12/STM4 operation.

Table 10 presents the functions of the module LEDs and port status LEDs.

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
All modules | REDUNDANT | Redundancy | Green | See Redundancy Status.
|  | NOTE: The REDUNDANT LED on the cOCx/STMx, FE-8, GE/FE, HSSI, OCx/STMx, and X.21/V.35 line modules is nonfunctional.
SRP module | POWER A OK | Power | Green | Power online on source A | Power off
| POWER B OK | Power | Green | Power online on source B | Power off
| FAN OK | Fan | Green | Fan online | Critical fan failure
| FAN FAIL | Fan | Red | Critical fan failure | Fan online
|  | NOTE: When the LED alternates between OK and FAIL at 10-second intervals, a noncritical fan failure exists.
| LINK | Ethernet | Green | Ethernet link up | Ethernet link down
| ACTIVITY | Ethernet | Green | Blinks when Ethernet traffic on link | No Ethernet traffic on link
Ethernet line modules | LINK | Ethernet | Green | Ethernet link up | Ethernet link down
ACTIVITY | Ethernet | Green | Blinks when Ethernet traffic on link | No Ethernet traffic on link
HSSI line module | SYNC | Port status | Green | 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 DCE, the LED lights when the DTE is 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 DCE, the LED goes out when the DTE becomes unavailable.
YEL ALM | NOTE: This LED is not functional on the HSSI line module.
RED ALM | Port status | Red | 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 DCE, the LED lights when the DTE becomes unavailable. | If the port is configured as DTE, the LED goes out when both the DCE and the clock source are available. If the port is configured as DCE, the LED goes out when the DTE is available.
X.21/V.35 line module | ACTIVE | Port status | Green | Port configured | Port not configured
LOOPBK | Port status | Yellow | Port in local loopback or remote loopback, depending on the type of connection. | Port not in loopback
ERROR | Port status | Red | Port is enabled or comes online | Port is disabled or goes offline
V.35 | Port status | Green | V.35 cable connected | V.35 cable disconnected
X.21 | Port status | Green | X.21 cable connected | X.21 cable disconnected
DCE | Port status | Green | DCE cable connected | DCE cable disconnected
DTE | Port status | Green | DTE cable connected | DTE cable disconnected
Other line modules | SYNC | Port status | Green | In frame | Not in frame
YEL ALM | Port status | Yellow | Far-end receive failure (FERF) exists | No FERF present
RED ALM | Port status | Red | Loss of sync/frame | In frame

The following figures show a representative module for each of the three variations:

- SRP module (Figure 49)
- Ethernet line module (Figure 50)
- Other line modules (Figure 51)

  Figure 49: SRP Module LEDs

  | Note: The primary SRP module illuminates the REDUNDANT LED only when the SRP module detects 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 (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. (ERX7xx and ERX14xx models only)

Figure 50: FE2 Module LEDs

Figure 51: E3 and T3 Module LEDs

## 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 | on (off for GE-2 LM and GE-HDE LM) | 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 at the next reboot.

Table 12: Troubleshooting Abnormal LED Activity on Modules

Diagnostic Signs | Possible Problems | Actions
--- | --- | ---
POWER A OK LED is not lit POWER B OK 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 Juniper Networks Customer Service.
FAIL LED lights | The line module and I/O module are incompatible. A hardware failure, such as a failed module. | Make sure that the line modules and I/O modules are compatible; replace if necessary. If you replaced the I/O module 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 Juniper Networks Customer Service.
FAN OK LED does not light FAN FAIL LED lights | Fan is not working properly or has slowed down. Fan needs replacement. | Contact Juniper Networks Customer Service; the system must be serviced.
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. Contact Juniper Networks Customer Service.
RED ALM is lit | 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 system. NOTE: Problem is corrected when normal LED activity occurs.
YEL ALM is lit NOTE: This LED is not functional on the HSSI line module. | Far end receive failure (FERF) exists. | Correct FERF problem. Reset system. NOTE: Problem is corrected when normal LED activity occurs.
System does not boot. Modules held offline. FAIL LED lights. | A slot group is overloaded. | Issue the show version command to display module status. Review section on proper slot group configuration in Installing Modules. Reconfigure system with correct slot group configuration. Reset system.
No LED indications or obvious signs. | 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 system.

## Redundancy Status

You can determine the redundancy state of line modules by examining the ONLINE and REDUNDANT status LEDs (ERX7xx and ERX14xx models only). See Table 13.

| Note: The REDUNDANT LED on the cOCx/STMx, FE-8, GE/FE, HSSI, and OCx/STMx modules is nonfunctional.

Table 13: Redundancy Status of a Line Module

ONLINE LED | REDUNDANT LED | State of the Line Module
--- | --- | ---
Off | Off | Module is booting or is an inactive primary line module.
On | Off | Module is active, but no standby module is available.
Off | On | Module is in standby state.
On | On | Module is active, and a standby module is available.