Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Troubleshooting an M120 FEB When a Chassis Alarm Is Lit Upon Initial Startup or Removal



Description: An FPC is mapped to an empty FEB slot, the red alarm LED on the chassis is lit:

The FPC mapped to an empty FEB slot (or to a FEB that is offline) comes online, but its Physical Interface Cards (PICs) do not, and the physical interfaces on those PICs are not created.


  • On startup, the red alarm LED is lit if an FPC slot is filled, but the corresponding FEB slot is empty.

  • The red alarm LED is lit if a FEB is removed before its connected FPCs are remapped to either another FEB or to none.

To eliminate the red alarm LED:

  1. Check the status of FEBs and determine whether each FPC is connected to an active FEB by entering the show chassis fpc-feb-connectivity command. By default, each FPC is associated with the FEB of the same identifying number; for example, FPC 1 to FEB 1.
  2. If necessary, change the default FPC-FEB connection by using the fpc-feb-connectivity statement at the [edit chassis] hierarchy level. You can also map an FPC to none to specify that the FPC is not mapped to any FEB. (When an FPC is configured not to connect to any FEB, interfaces on that FPC are not created; however, no alarm is triggered.)
  3. Verify that the associated physical interfaces are created by entering the show interfaces terse command.

For more information about configuring FPC-FEB connectivity, see the Junos OS Administration Library.