This article describes about why interfaces go down on FPC and how to identify the problem if logs are rolled over. Also how to solve the problem.

Interfaces will show down due to ASIC error.

Physical interface: et-1/0/0, Enabled, Physical link is Down
<>
 Device flags  : Present Running Down ASIC-Error

Physical interface: et-1/0/2, Enabled, Physical link is Down
<>
 Device flags  : Present Running Down ASIC-Error

Physical interface: et-1/0/4, Enabled, Physical link is Down
 <>
Device flags  : Present Running Down ASIC-Error

Physical interface: et-1/0/6, Enabled, Physical link is Down
<>
 Device flags  : Present Running Down ASIC-Error


Physical interface: et-1/0/8, Enabled, Physical link is Down
<>
 Device flags  : Present Running Down ASIC-Error

Logs are rolled over but we can check "show chassis fpc errors <fpc-slot no.>"

username@hostname> show chassis fpc errors 1 

FPC Scope  Category  Level Occurred Cleared Threshold Action-Taken Action

Pfe-State: pfe-0 -DISABLED | pfe-1 -ENABLED | pfe-2 -ENABLED | pfe-3 -ENABLED | pfe-4 -ENABLED | pfe-5 -ENABLED | 

Please reboot the FPC to bring interface up and enable PFE.

> request chassis fpc slot 0 restart