In EVPN all-active multihoming environments, when a virtual gateway MAC (VGA-MAC) is configured under IRB interfaces, traffic loss can occur during MAC table age out and re-ARP processes. This issue affects the stability of network connectivity and can lead to service disruptions.

1. Intermittent traffic loss observed in EVPN all-active multihoming setups.
2. Traffic disruptions coinciding with MAC table ageout events.
3. Inconsistent ARP synchronization between multihomed devices.
4. MAC-IP routes being deleted and re-added, causing temporary routing inconsistencies.

• Consider using Anycast IP instead of VGA-MAC for improved stability.
• Adjust MAC aging timers to align with ARP/MAC-IP aging timers to reduce the frequency of re-ARP events.
• Implement the following configuration change on MX Series routers (note: not applicable to PTX Series):

set routing-options forwarding-table export EVPN_RT_TYPE_2_NO_GATEWAY
set policy-options policy-statement EVPN_RT_TYPE_2_NO_GATEWAY term 1 from protocol evpn
set policy-options policy-statement EVPN_RT_TYPE_2_NO_GATEWAY term 1 from route-type mac-ip
set policy-options policy-statement EVPN_RT_TYPE_2_NO_GATEWAY term 1 then reject

This issue is also explained in following PR:

https://prsearch.juniper.net/PR1691132

Traffic drop is observed in the EVPN-MPLS active-active multihoming scenario when re-ARP is sent from one MH (MH1), an ARP reply is received on another MH (MH2) and it is not synced to MH1 which triggers MAC-IP deletion and addition. To identify the issue, execute the CLI command "show mac-vrf forwarding mac-ip-table".

Restoration-Steps: Restart the routing process.

Resolved-In : evo:23.1R1-EVO evo:24.2R2-EVO junos:22.4R3 junos:23.1R1 junos:24.3R1