Monitor Hardware Components
If the System Control Board (SCB), System and Switch Board (SSB), or Forwarding Engine Board (FEB) is not running, information about chassis components is not available through the command-line interface (CLI).
To use the CLI to monitor Juniper Networks routers, follow these steps:
Log in to the router. The CLI operational mode prompt (>) appears.
If the operational mode prompt does not appear when you log in to the router, type cli to start the Junos OS and enter operational mode. The prompt changes to >, indicating that you are in operational mode.
Use one of the operational mode CLI commands listed in Operational Mode CLI Commands for Router Monitoring to monitor router hardware.