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T4000 Troubleshooting Resources Overview


To troubleshoot a T4000 router, you use the Junos OS command-line interface (CLI), LCD, alarms, devices connected to the alarm relay contacts, and LEDs on both the components and craft interface.

  • LEDs—When the Routing Engine detects an alarm condition, it lights the red or yellow alarm LED on the craft interface as appropriate. In addition, you can also use the component-specific LEDs on the craft interface and on the faceplate of a component to troubleshoot the router.

  • LCD—When a red or yellow alarm occurs, the cause of the alarm messages is displayed on the craft interface LCD. Use the CLI to display more information about the alarm.

  • Alarm devices connected to the alarm relay contact—When a red or yellow alarm occurs, it trips the corresponding alarm relay contact.

  • CLI—The CLI is the primary tool for controlling and troubleshooting hardware, Junos OS, routing protocols, and network connectivity. CLI commands display information from routing tables, information specific to routing protocols, and information about network connectivity derived from the ping and traceroute utilities. For information about using the CLI to troubleshoot Junos OS, see the appropriate Junos OS configuration guide.

  • JTAC—If you need assistance during troubleshooting, you can contact the Juniper Networks Technical Assistance Center (JTAC) by using the Web or by telephone. If you encounter software problems, or problems with hardware components not discussed here, contact JTAC.