Technical Tip: Best practice HA monitored interface configuration for LACP interface that is used for multicast traffic.

[acvaldez]

Description	This article will serve as a guide on how to configure the LACP interface on HA-monitored interfaces when LACP is used for multicast traffic.
Scope	FortiGate
Solution	Below shows the interfaces that are part of the  LACP configuration. FGTA-MCAST # diag netlink aggregate name LACPMcastServer status: up npu: n flush: n asic helper: y ports: 2 link-up-delay: 50ms min-links: 1 ha: master distribution algorithm: L4 LACP mode: static slave: port3   index: 0   link status: up   link failure count: 0   permanent MAC addr: 00:0c:29:09:75:6f slave: port4   index: 1   link status: up   link failure count: 0   permanent MAC addr: 00:0c:29:09:75:79 - On HA configuration instead of placing the LACP interface, the individual interfaces are configured that is a member of the LACP. FGTA-MCAST (ha) # show config system ha     set group-name "FGT_Multicast"     set mode a-p     set password ENC      set hbdev "port5" 0     set ha-mgmt-status enable     config ha-mgmt-interfaces         edit 1             set interface "port1"             set gateway 100.100.100.2         next     end     set override enable     set priority 200     set monitor "port2" "port3" "port4" end -With this configuration, if failover is triggered from Primary to Secondary FortiGate the multicast traffic will establish without any delay.  # get sys ha stat HA Health Status: OK Model: FortiGate-VM64 Mode: HA A-P Group: 0 Debug: 0 Cluster Uptime: 0 days 0:30:17 Cluster state change time: 2022-06-17 21:32:28 Primary selected using:<2022/06/17 21:32:28> FGVM04TM22004042 is selected as the primary because it has the largest value of override priority. -Screenshot of the Multicast traffic when a failover was done. Note: If the LACP interface itself is used on the HA monitored interfaces, HA monitoring will have a delay when detecting the LACP interface and can cause some delays to establish LACP traffic during a FortiGate HA failover.