On QFX10K (QFX10002, QFX10008, QFX10016), testing the connectivity between the REs and FPC might be used as a health check step. It helps to verify that the Routing Engines are able to reach/communicate with the FPCs.
To test connectivity from the RE to all FPCs, issue the following command
test chassis routing-engine fpc-connectivity re-slot <> fpc all
Example:
root@qfx10002-re0> test chassis routing-engine fpc-connectivity re-slot 0 fpc all FPC 0 is reachable from RE slot 0 FPC 1 is reachable from RE slot 0 FPC 6 is reachable from RE slot 0 FPC 7 is not reachable from RE slot 0 root@qfx10002-re0> test chassis routing-engine fpc-connectivity re-slot 1 fpc all FPC 0 is reachable from RE slot 1 FPC 1 is reachable from RE slot 1 FPC 6 is reachable from RE slot 1 FPC 7 is not reachable from RE slot 1
You can also test the connectivity from a specific RE to a specific FPC by issuing the following command
test chassis routing-engine fpc-connectivity re-slot <> fpc fpc-slot <>
root@qfx10002-re0> test chassis routing-engine fpc-connectivity re-slot 0 fpc fpc-slot 0 FPC 0 is reachable from RE slot 0