GARP(Gratuitous ARP) is not sent out in the management interfaces (reX:mgmt-0) upon mastership switchover for the shared IP address between the routing-engines  

After executing the routing-engine mastership switchover on JUNOS EVO devices configured with a shared "master-only" IP address between both routing-engine management interfaces (reX:mgmt-0), the GARP (Gratuitous ARP) messages will fail to be sent out by the new master routing-engine (reX:mgmt-0) interface to the shared broadcast domain. Consequently, other nodes in the segment will not update their arp table with the new master MAC address.

This will lead to some packet drops destined for the management shared IP address until the ARP entry is updated with the corresponding MAC address of the new master routing-engine.

The GARP feature on management interfaces for JUNOS EVO is corrected in new EVO releases