如果两节点的上联交换机允许组播，采用组播模式（默认）
mcast_src_ip 发送多播包的地址，如果不设置默认使用绑定网卡的primary ip
如果两节点的上联交换机禁用了组播，则只能采用vrrp单播通告的方式
###########################
unicast_src_ip xx.xx.xx.xx
unicast_peer {
xx.xx.xx.xx
}
#############################
关于keepalived监测脚本的WARNING：
Unsafe permissions found for script '/etc/keepalived/check_mysql.sh'.
SECURITY VIOLATION - scripts are being executed but script_security not enabled. There are insecure scripts.
Keepalived两节点出现双VIP的情况
https://www.cnblogs.com/netonline/archive/2017/10/09/7642595.html
keepalived 配置文件参数详解
https://blog.csdn.net/mofiu/article/details/76644012
https://www.cnblogs.com/along1226/p/5027838.html
MySQL共享存储主备模式利用Keepalived实现双机高可用
http://blog.51cto.com/7424593/1893767
keepalived Unsafe permissions found for script
http://old.gebiji.com/2016/12/21/ka-warning-default-user/
How do I enable: script_security?
https://github.com/acassen/keepalived/issues/901
Keepalived+Nginx架构整理版
https://linuxeye.com/448.html
LVS的原理介绍
https://www.cnblogs.com/along1226/p/5014363.html
