Keepalived 单播模式实战：跨网络高可用的关键配置

keepalived的单播模式

为什么要单播，组播模式使用的网址资源最少，但是不能跨网络，如果主备两台主机是跨网络的，那么只能启用单播来实现vrrp通告

bash 复制代码

#在KA1中
[root@KA1 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
     123456789@163.com
   }
   notification_email_from 123456789@163.com
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id KA1
   vrrp_skip_check_adv_addr
   #vrrp_strict
   vrrp_garp_interval 1
   vrrp_gna_interval 1
   #vrrp_mcast_group4 224.0.0.44			#关闭组播
}

vrrp_instance WEB_VIP {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    unicast_src_ip 172.25.254.50		#指定单播源地址，通常是本机IP
    unicast_peer {
      172.25.254.60						#指定单播接收地址
    }
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        172.25.254.100/24 dev eth0 label eth0:0
    }
}

#在KA2中
[root@KA2 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
     123456789@163.com
   }
   notification_email_from 123456789@163.com
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id KA2
   vrrp_skip_check_adv_addr
   #vrrp_strict
   vrrp_garp_interval 1
   vrrp_gna_interval 1
   #vrrp_mcast_group4 224.0.0.44			#关闭组播
}

vrrp_instance WEB_VIP {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 80
    advert_int 1
    unicast_src_ip 172.25.254.60		#指定单播源地址，通常是本机IP
    unicast_peer {
      172.25.254.50						#指定单播接收地址
    }
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        172.25.254.100/24 dev eth0 label eth0:0
    }
}

[root@KA1 ~]# systemctl restart keepalived.service
[root@KA2 ~]# systemctl restart keepalived.service

#测试
#在KA1中开启独立shell监控播报信息
[root@KA1 ~]# tcpdump -i eth0 -nn src host 172.25.254.50 and dst 172.25.254.60

#在KA2中开启独立shell监控播报信息
[root@KA2 ~]# tcpdump -i eth0 -nn src host 172.25.254.60 and dst 172.25.254.50


#在KA1正常时
#ka2播报信息不显示通告内容

[root@KA1 ~]# systemctl stop keepalived.service

#vip会被迁移到KA2,KA2上开始显示播报内容

[root@KA1 ~]# systemctl start keepalived.service

#vip因为优先级被KA1抢占，KA2中播报停止

模式	通信方式	适用场景
组播 (mcast_group4)	向组播地址`224.x.x.x`发送报文	局域网允许组播；多节点集群；简单
单播 (unicast_src_ip + unicast_peer)	两台机器点对点 IP 通信	云环境、防火墙屏蔽组播的环境；必须填写对端真实 IP