This article helps to understand the MC-Lag consistency-check command behavior in EX and QFX.
Customer may experience associated LAG/AE member down when issuing MC-Lag consistency-check command.
Sep 14 19:58:26 ex mgd[27041]: UI_CMDLINE_READ_LINE: User 'xxx', command 'set multi-chassis mc-lag consistency-check '
Sep 14 19:58:41 ex mgd[27041]: UI_COMMIT_COMPLETED: : commit complete
Sep 14 20:01:52 ex mclag_cfgchkd[28236]: MCLAG_CFGCHKD_MANDATORY_CONSISTENCY_CHECK_FAILED: Mismatch detected in vlan membership config, error_code 45
Sep 14 20:01:55 ex mib2d[14295]: SNMP_TRAP_LINK_DOWN: ifIndex 878, ifAdminStatus up(1), ifOperStatus down(2), ifName aeX
As you can observe, soon after the consistency failed logs, ae interface went down. As per the below Juniper article this is expected behavior that if there is any mismatch then respective mc-ae will be marked as down. Please go through the below Juniper article for the same.
Advanced MC-LAG Concepts | Junos OS | Juniper Networks
Note: Please do not run this command in production in MC-LAG environment until unless there is no mismatch between the peers as this will cause the impact.
Therefore, we request that you use the command "set multi-chassis mc-lag consistency-check" only after resolving the mismatches between MC-Lag peers. You can also set a delay time for the consistency check. Please refer to the Juniper article mentioned above for further clarification.
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