This article provided steps to detect FEC alignment errors permanently bringing down the interface to the QFX5200 platform.

This QFX5200 100G ports down with LOCAL-FAULT often with AE member link flap

-Need to dump the register output [include * as well to dump all the register], steps below

cprod -A FPC0 -c 'sho dcbcm ifd all'. -- Take the corresponding port-name from the output

Example:

root@jtac-qfx5200-32c-32q-r2033:RE:0% cprod -A FPC0 -c 'sho dcbcm ifd all'

 ----------------------------------------------------------

 ifd name   global-dev local-dev  port-num  port-name 

 ----------------------------------------------------------

 et-0/0/0       0     0     50   ce36  <<<<<<<<<

 pfe-0/0/0       0     0     0   cpu0

 pfh-0/0/0       0     0     0   cpu0

 sxe-0/0/0       0     0    100    ge1

 sxe-0/0/1       0     0     66    ge0

root@jtac-qfx5200-32c-32q-r2033:RE:0%

root@jtac-qfx5200-32c-32q-r2033:RE:0%cprod -A FPC0 -c 'set dcbcm bcm "phy ce36 *"'

From the above command output:

Issue state register dump:

RX_X1_FEC_ALGN_FSM_STr [0x701092b0] = 0x00dc

  CL91_FEC_ALGN_FSM_LIVE_STATE<2:0>=0x4

  CL91_FEC_ALGN_FSM_LATCHED_STATE<9:3>=0x1b

non-issue state register dump:

RX_X1_FEC_ALGN_FSM_STr [0x701092b0] = 0x03dc

  CL91_FEC_ALGN_FSM_LIVE_STATE<2:0>=0x4

  CL91_FEC_ALGN_FSM_LATCHED_STATE<9:3>=0x7b

Related PR: https://prsearch.juniper.net/problemreport/PR1725116
Related KB: https://supportportal.juniper.net/s/article/QFX5200-100g-interfaces-remain-down-after-a-reboot