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Troubleshooting the EX4650 Components

Alarm Types and Severity Levels

The QFX Series switches support different alarm types and severity levels. Table 1 provides a list of alarm terms and definitions that may help you in monitoring the device.

Table 1: Alarm Terms and Definitions




Signal that alerts you to conditions that might prevent normal operation. On the device, alarm indicators might include an LCD panel and LEDs on the device. The LCD panel (if present on the device) displays the chassis alarm message count. Blinking amber or yellow LEDs indicate yellow alarm conditions for chassis components.

Alarm condition

Failure event that triggers an alarm.

Alarm severity levels

Seriousness of the alarm. The level of severity can be either major (red) or minor (yellow).

  • Major (red)—Indicates a critical situation on the device that has resulted from one of the following conditions. A red alarm condition requires immediate action.

    • One or more hardware components have failed.

    • One or more hardware components have exceeded temperature thresholds.

    • An alarm condition configured on an interface has triggered a critical warning.

  • Minor (yellow or amber)—Indicates a noncritical condition on the device that, if left unchecked, might cause an interruption in service or a degradation in performance. A yellow alarm condition requires monitoring or maintenance. For example, a missing rescue configuration generates a yellow system alarm.

Alarm types

Alarms include the following types:

  • Chassis alarm—Predefined alarm triggered by a physical condition on the device such as a power supply failure or excessive component temperature.

  • Interface alarm—Alarm that you configure to alert you when an interface link is down. Applies to ethernet, fibre-channel, and management-ethernet interfaces. You can configure a red (major) or yellow (minor) alarm for the link-down condition, or have the condition ignored.

  • System alarm—Predefined alarm that might be triggered by a missing rescue configuration, failure to install a license for a licensed software feature, or high disk usage.

Interface Alarm Messages

Interface alarms are alarms that you configure to alert you when an interface is down.

To configure an interface link-down condition to trigger a red or yellow alarm, or to configure the link-down condition to be ignored, use the alarm statement at the [edit chassis] hierarchy level. You can specify the ethernet, fibre-channel, or management-ethernet interface type.


Fibre Channel alarms are valid only on QFX3500 devices.


When red alarms or major alarms are issued on QFX5100 or EX4600 switches, the alarm LED glows amber instead of red.

By default, major alarms are configured for interface link-down conditions on the control plane and management network interfaces in a QFabric system. The link-down alarms indicate that connectivity to the control plane network is down. You can configure these alarms to be ignored using the alarm statement at the [edit chassis] hierarchy level.


If you configure a yellow alarm on the QFX3008-I Interconnect device, it is handled as a red alarm.

Create an Emergency Boot Device

Before you begin, you need to download the installation media image for your device and Junos OS release from

If Junos OS on the device is damaged in some way that prevents the software from loading properly, you can use an emergency boot device to repartition the primary disk and load a fresh installation of Junos OS. Use the following procedure to create an emergency boot device.


In the following procedure, we assume that you are creating the emergency boot device on a switch. You can create the emergency boot device on another Juniper Networks switch or router, or any PC or laptop that supports Linux. The steps you take to create the emergency boot device vary, depending on the device.

To create an emergency boot device:

  1. Use FTP to copy the installation media image into the /var/tmp directory on the device.
  2. Insert a USB device into the USB port.
  3. From the Junos OS CLI, start the shell:
  4. Switch to the root account using the su command:

    The password is the root password for the device. If you logged in to the device as root, you do not need to perform this step.

  5. Enter the following command on the device:

    The device writes the installation media image to the USB device:

  6. Log out of the shell: