This KB describes the issue which traffic loss is seen with syslog message BRCM_NH_ECMP_THRESHOLD_REACHED when using ECMP on EX2300. This is a software bug that failed to release old entries of ECMP and as a result, it exceeded the maximum limit.

On EX2300 which enabled ECMP, syslog message below might be seen with traffic loss even if not that many ECMP entries are being used.

Nov 24 14:48:40 Switch dc-pfe[7166]: BRCM_NH_ECMP_THRESHOLD_REACHED: Maximum number of ECMP entries reached, nh_idx:131070
Nov 24 14:50:40 Switch dc-pfe[7166]: BRCM_NH_ECMP_THRESHOLD_REACHED: Maximum number of ECMP entries reached, nh_idx:131071
Nov 24 14:52:40 Switch dc-pfe[7166]: BRCM_NH_ECMP_THRESHOLD_REACHED: Maximum number of ECMP entries reached, nh_idx:131070

The trigger is vary, but for example below could be a trigger:

-Modifying OSPF metric and reverting it to ECMP path.
-Delation of ECMP entries by L3 protocol flaps.
-Rebooting the setup.

Above trigger would lead to issue state when EX2300 fails to release old ECMP entries.

The issue has been resolved by a software fix provided by PR1833502.

https://prsearch.juniper.net/problemreport/PR1833502

2025-02-18 : Modified KB as got a software fix and published it.
2024-10-22 : Article Created