Ports blocked by storm control despite thresholds are not exceeded

The behavior was reported on 18.4R3-S1.3 with the following configuration.

set forwarding-options storm-control-profiles storm_control all bandwidth-level 20000

set forwarding-options storm-control-profiles storm_control action-shutdown

Traffic was not exceeding 8Mbps and ports went down despite storm control threshold is 20Mbps.

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_IN_EFFECT: ge-1/0/25.0: storm control in effect on the port

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_DISABLED: ge-1/0/25.0: storm control disabled port

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_IN_EFFECT: ge-1/0/27.0: storm control in effect on the port

<TimeStamp hostname> mib2d[xxxx]: SNMP_TRAP_LINK_DOWN: ifIndex 652, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-1/0/25

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_IN_EFFECT: ge-1/0/25.0: storm control in effect on the port

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_IN_EFFECT: ge-1/0/27.0: storm control in effect on the port

<TimeStamp hostname> mib2d[xxxx]: SNMP_TRAP_LINK_DOWN: ifIndex 1017, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-5/0/0

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_IN_EFFECT: ge-2/0/24.0: storm control in effect on the port

<TimeStamp hostname> l2ald[xxxx]: L2ALD_ST_CTL_DISABLED: ge-2/0/24.0: storm control disabled port

The version is matching several bugs related to storm-control

https://prsearch.juniper.net/problemreport/PR1564020 >>> Fixed on 18.4R3-S7. This code is end of support.

https://prsearch.juniper.net/problemreport/PR1493173 >>> Fixed on 18.4R3-S3. This code is end of support.

https://prsearch.juniper.net/problemreport/PR1552815 >>> Fixed on 18.4R3-S7. This code is end of support.

After an upgrade to a supported release 21.4R3.15, the issue was not observed anymore.