On S5720-32C-HI-24S-AC, to achieve the recovery time within the required 50ms,currently 17 BFD sessions are configured for VRRP and it working fine. As soon as customer configure another BFD sessions for newly added Vlanif all the BFD sessions starts flapping randomly.

Apr 4 2018 17:27:48+03:00 ICC-LAN-UP-1 %BFD/4/STACHG_TODWN(l)[49]:BFD session changed to Down. (SlotNumber=0, Discriminator=8197, Diagnostic=DetectDown, Applications=VRRP | AUTO, ProcessPST=False, BindInterfaceName=Vlanif166, InterfacePhysicalState=Up, InterfaceProtocolState=Up)
Apr 4 2018 17:27:48+03:00 ICC-LAN-UP-1 %BFD/4/STACHG_TOUP(l)[50]:BFD session changed to Up. (SlotNumber=0, Discriminator=8197, FormerStatus=Down, Applications=VRRP | AUTO, BindInterfaceName=Vlanif166, ProcessPST=False)
Apr 4 2018 17:27:48+03:00 ICC-LAN-UP-1 %BFD/4/STACHG_TODWN(l)[51]:BFD session changed to Down. (SlotNumber=0, Discriminator=8210, Diagnostic=DetectDown, Applications=VRRP | AUTO, ProcessPST=False, BindInterfaceName=Vlanif15, InterfacePhysicalState=Up, InterfaceProtocolState=Up)
Apr 4 2018 17:27:48+03:00 ICC-LAN-UP-1 %BFD/4/STACHG_TOUP(l)[52]:BFD session changed to Up. (SlotNumber=0, Discriminator=8210, FormerStatus=Down, Applications=VRRP | AUTO, BindInterfaceName=Vlanif15, ProcessPST=False)


On S5720-Hi,BFD process by software. Ff you want that the VRRP recovery time should be within 50ms, you need to add command "set service-mode enhanced ", with this command bfd is processed by hardware.

<HUAWEI> system-view
[HUAWEI] set service-mode enhanced
Warning: This command will effect forward performance. Continue? [Y/N]:y