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.
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 11 presents the functions of the module LEDs and port status LEDs.
Table 11: 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:
Figure 49: SRP Module LEDs

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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. (ERX-7xx and ERX-14xx models only) |
Figure 50: FE2 Module LEDs

Figure 51: E3 and T3 Module LEDs

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 12 and Table 13 to understand normal and abnormal LED activity.
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Note: When you reboot the system after installing a new version of the software, the line modules appear to boot twice. |
Table 12: Normal Activity of Functional Status LEDS During Booting
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 13: Troubleshooting Abnormal LED Activity on Modules
|
Diagnostic Signs |
Possible Problems |
Actions |
|---|---|---|
|
|
|
|
FAIL LED lights |
|
|
|
|
Contact Juniper Networks Customer Service; the system must be serviced. |
|
LINK LED is not lit |
|
|
|
RED ALM is lit |
|
|
|
YEL ALM is lit NOTE: This LED is not functional on the HSSI line module. |
|
|
|
|
|
|
No LED indications or obvious signs. |
|
|
You can determine the redundancy state of line modules by examining the ONLINE and REDUNDANT status LEDs (ERX-7xx and ERX-14xx models only). See Table 14.
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Note: The REDUNDANT LED on the cOCx/STMx, FE-8, GE/FE, HSSI, and OCx/STMx modules is nonfunctional. |
Table 14: Redundancy Status of a Line Module