Overview of Troubleshooting Resources for the M120 Router

Troubleshooting Using the Command-Line Interface

The Junos OS command-line interface (CLI) is the primary tool for controlling and troubleshooting router hardware, the 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.

You enter CLI commands on one or more external management devices connected to the Routing Engine through ports on the Craft Interface. The port labeled AUX attaches the Routing Engine to a laptop, modem, or other auxiliary device, the port labeled CONSOLE attaches to a system console, and the port labeled ETHERNET attaches to a management LAN. For more information, see M120 Routing Engine Description.

For information about using the CLI to display details about alarms generated by interfaces and hardware components, see Troubleshooting Using the Chassis and Interface Alarm Messages.

For information about using the CLI to troubleshoot the Junos OS, see the appropriate Junos OS configuration guide.

Troubleshooting Using the Chassis and Interface Alarm Messages

When the Routing Engine detects an alarm condition, it lights the red or yellow alarm LED on the craft interface as appropriate. To view a more detailed description of the alarm cause, issue the show chassis alarms CLI command:

There are two classes of alarm messages:

• Chassis alarms—Indicate a problem with a chassis component such as the cooling system or power supplies.
• Interface alarms—Indicate a problem with a specific network interface.

Troubleshooting Using the Juniper Networks Technical Assistance Center

If you need assistance during troubleshooting, you can contact the Juniper Networks Technical Assistance Center (JTAC) by using the Web or by telephone. See Contacting Customer Support.