Symptom

1.For normal behavior, if we insert QSFP-100G-ER4L-S, it will auto-enable FEC mode, and for QSFP28 100G LR4, it will not auto-enable FEC mode. 2.if we insert QSFP-100G-ER4L-S, then remove and insert QSFP28 100G LR4, the FEC mode not clear and keep enable. RP/0/RP0/CPU0:NCS-55A1-2#show controllers fia diagshell 1 "phy ce69 *" location 0/0/cPU0 | in FEC_MODE <<<< Before insert ER4L module Thu May 20 12:11:21.606 UTC R_CL91_FEC_MODE=0x0 T_CL91_FEC_MODE=0x0 CL91_FEC_MODE=0x0 CL91_FEC_MODE=0x0 RP/0/RP0/CPU0:NCS-55A1-2# LC/0/0/CPU0:May 20 12:34:54.410 UTC: optics_driver[203]: %L2-OPTICS-6-TRANSCEIVER_INSERTED : Optics module HundredGigE0/0/0/18 type QSFP28 100G ER4L inserted RP/0/RP0/CPU0:NCS-55A1-2#show controllers fia diagshell 1 "phy ce69 *" location 0/0/cPU0 | in FEC_MODE <<<<<<< After insert ER4L module Thu May 20 12:35:04.677 UTC R_CL91_FEC_MODE=0x4 T_CL91_FEC_MODE=0x4 CL91_FEC_MODE=0x4 CL91_FEC_MODE=0x4 RP/0/RP0/CPU0:NCS-55A1-2#LC/0/0/CPU0:May 20 12:35:13.030 UTC: optics_driver[203]: %L2-OPTICS-2-TRANSCEIVER_REMOVED : Optics module HundredGigE0/0/0/18 type QSFP28 100G ER4L removed RP/0/RP0/CPU0:NCS-55A1-2# RP/0/RP0/CPU0:NCS-55A1-2#show controllers fia diagshell 1 "phy ce69 *" location 0/0/cPU0 | in FEC_MODE <<<<<< After ER4L module remove. Thu May 20 12:35:16.355 UTC R_CL91_FEC_MODE=0x4 T_CL91_FEC_MODE=0x4 CL91_FEC_MODE=0x4 CL91_FEC_MODE=0x4 LC/0/0/CPU0:May 21 17:36:56.253 UTC: optics_driver[203]: %L2-OPTICS-6-TRANSCEIVER_INSERTED : Optics module HundredGigE0/0/0/18 type QSFP28 100G LR4 inserted RP/0/RP0/CPU0:NCS-55A1-2#show controllers fia diagshell 1 "phy ce69 *" location 0/0/CPU0 | include FEC_MODE Fri May 21 17:36:59.784 UTC R_CL91_FEC_MODE=0x4 T_CL91_FEC_MODE=0x4 CL91_FEC_MODE=0x4 CL91_FEC_MODE=0x4

Conditions

NA

Workaround

1.HW reload LC if it's 1U router like NCS55A1 need to reload the whole chassis. 2.Or configure "fec none" before remove these optical module ER4L-S, then remove optical module , then delete configuration "no fec".

Further Problem Description