Configure Keepalived Dual‑Host Mode for Automatic VIP Failover

Overview

The article explains a Keepalived dual‑host (master‑master) setup that demonstrates VIP address movement. Two servers (ka1 and ka2) run Keepalived with two VRRP instances, each acting as master for one virtual router and backup for the other.

Environment

ka1 and ka2 are two separate Keepalived servers.

Each server hosts a virtual router with two VRRP instances that are master/backup of each other.

ka1 Keepalived Configuration

yum install -y keepalived
cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
   [email protected]
   }
   notification_email_from [email protected]
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id ka1
   vrrp_mcast_group4 224.100.100.100 
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 66
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.16.0.100/24 dev ens33 label ens33:1
    }
}

vrrp_instance VI_2 {
    state BACKUP
    interface ens33
    virtual_router_id 88
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 654321
    }
    virtual_ipaddress {
        172.16.0.200/24 dev ens33 label ens33:2
    }
}

cat /etc/hosts
10.0.0.125 ka1
10.0.0.126 ka2
ssh-keygen
ssh-copy-id 10.0.0.126

ka2 Keepalived Configuration

yum install -y keepalived
cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
   [email protected]
   }
   notification_email_from [email protected]
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id ka1
   vrrp_mcast_group4 224.100.100.100 
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 66
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.16.0.100/24 dev ens33 label ens33:1
    }
}

vrrp_instance VI_2 {
    state MASTER
    interface ens33
    virtual_router_id 88
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 654321
    }
    virtual_ipaddress {
        172.16.0.200/24 dev ens33 label ens33:2
    }
}

cat /etc/hosts
10.0.0.125 ka1
10.0.0.126 ka2
ssh-keygen
ssh-copy-id 10.0.0.125

Verification – Observe VIP Migration

Start Keepalived on ka1:

systemctl start keepalived
ip a

Both VIPs (172.16.0.100 and 172.16.0.200) appear on ens33 of ka1.

Start Keepalived on ka2:

systemctl start keepalived
ip a

Now ka2 becomes MASTER for VI_2 and takes over the VIP 172.16.0.200, while ka1 retains VIP 172.16.0.100.

VRRP Multicast Advertisement Capture

tcpdump -i ens33 -nn host 224.100.100.100

The capture shows VRRP advertisements from both servers with their respective virtual router IDs and priorities, confirming the failover behavior.