# VRRP and Load Balancing configuration in Keepalived

###### tags: `vrrp` `keepalived` `linux`

We use the Keepalived for high availability and load balancing. This is a simple scenario; two load balance servers and multiple back-end servers (eg. nginx web server). The load balance servers need two NICs for connecting public network and private network.

### On the both load balancer, enable "ip_non_local_bind" and "ip_forward".

echo 1 > /proc/sys/net/ipv4/ip_nonlocal_bind
echo 1 > /proc/sys/net/ipv4/ip_forward

### keepalived.conf on the Load Balancer 1 (lb1)

root@lb1:~# cat /etc/keepalived/keepalived.conf
global_defs {
    notification_email {
        [e-mail]
    }
    notification_email_from [e-mail]
    smtp_server host
    smtp_connect_timeout 30
    lvs_id lvs_1
}

vrrp_instance vip1 {
    state MASTER
    interface enp0s8
    virtual_router_id 51
    priority 101
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass my_pass
    }
    virtual_ipaddress {
        192.168.56.100
    }
}

vrrp_instance vip2 {
    state MASTER
    interface enp0s3
    virtual_router_id 52
    priority 101
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass my_pass
    }
    virtual_ipaddress {
        10.0.2.100
    }
}

virtual_server 192.168.56.100 80 {
    delay_loop 5
    lb_algo rr
    lb_kind NAT
    protocol TCP
    persistence_timeout 10

    real_server 10.0.2.103 80 {
        TCP_CHECK {
            connect_timeout 3
        }
    }
    real_server 10.0.2.104 80 {
        TCP_CHECK {
            connect_timeout 3
        }
    }
}

### keepalived.conf on the Load Balancer 2 (lb2)

root@lb2:~# cat /etc/keepalived/keepalived.conf
global_defs {
    notification_email {
        [e-mail]
    }
    notification_email_from [e-mail]
    smtp_server host
    smtp_connect_timeout 30
    lvs_id lvs_1
}

vrrp_instance vip1{
    state MASTER
    interface enp0s8
    virtual_router_id 51
    priority 100
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass my_pass
    }
    virtual_ipaddress {
        192.168.56.100
    }
}

vrrp_instance vip2 {
    state MASTER
    interface enp0s3
    virtual_router_id 52
    priority 100
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass my_pass
    }
    virtual_ipaddress {
        10.0.2.100
    }
}

virtual_server 192.168.56.100 80 {
    delay_loop 5
    lb_algo rr
    lb_kind NAT
    protocol TCP
    persistence_timeout 10

    real_server 10.0.2.103 80 {
        TCP_CHECK {
            connect_timeout 3
        }
    }
    real_server 10.0.2.104 80 {
        TCP_CHECK {
            connect_timeout 3
        }
    }
}