keepalived: BACKUP send a G-ARP of VIP after a temporary network issue

Issue

• keepalived: BACKUP send a G-ARP of VIP after a temporary network issue

As a sample configuration, there are 2 hosts, lvs1 and lvs2 and lvs1 has a VIP.

lvs1:/etc/keepalived/keepalived.conf

vrrp_instance VI_1 {
  interface ens3
  state BACKUP
  virtual_router_id 51
  priority 150
  nopreempt
  virtual_ipaddress {
    192.168.122.100
  }
}

lvs2:/etc/keepalived/keepalived.conf

vrrp_instance VI_1 {
  interface ens3
  state BACKUP
  virtual_router_id 51
  priority 100
  nopreempt
  virtual_ipaddress {
    192.168.122.100
  }
}

When a temporary network issue happens, lvs2 become MASTER and send G-ARP(Gratuitous ARP) of VIP and goes back to BACKUP soone. However MASTER lvs1 sometimes doesn't notice it depending on the timing. In such case, the G-ARP from lvs2 adversely affect the network.

lvs2: /var/log/messages

Jul 20 11:17:41 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) Entering MASTER STATE
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) setting protocol VIPs.
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: Sending gratuitous ARP on ens3 for 192.168.122.100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens3 for 192.168.122.100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: Sending gratuitous ARP on ens3 for 192.168.122.100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: Sending gratuitous ARP on ens3 for 192.168.122.100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: Sending gratuitous ARP on ens3 for 192.168.122.100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: Sending gratuitous ARP on ens3 for 192.168.122.100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) Received advert with higher priority 150, ours 100
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jul 20 11:17:42 lvs2 Keepalived_vrrp[3476]: VRRP_Instance(VI_1) removing protocol VIPs.

lvs1 doesn't have any log entry in /var/log/messages.