keepalived实现原理
keepalived采用vrrp热备份协议，实现Linux服务器的多机热备功能
vrrp，虚拟路由冗余协议，是针对路由器的一种备份解决方案
keepalivd案列讲解
keepalived可实现多机热备，每个热备组有多台服务器，最常用的就是双机热备
双机热备的故障切换是由虚拟IP地址的漂移来实现，适用于各种应用服务器
DR模式原理
实验环境
CentOS7系统：
DR1 主： 192.168.100.2
DR2 备： 192.168.100.20
虚拟IP：192.168.100.10
web1：192.168.100.221
web2：192.168.100.222
win10系统：
client：192.168.100.1001、分别在四台Linux虚拟机上安装实验所需软件包
DR1主：
[root@localhost ~]# yum install ipvsadm keepalived -y
DR2从：
[root@localhost ~]# yum install ipvsadm keepalived -y
web1：
[root@localhost ~]# yum install httpd -y
web2：
[root@localhost ~]# yum install httpd -y2、分别将五台虚拟机的网络模式改为仅主机模式（五台操作相同）
3、分别修改四台Linux虚拟机的IP地址
DR1主：
[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static #dhcp改为static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens33
UUID=3ceed540-b04c-48d6-a4f7-79951f09ea1d
DEVICE=ens33
ONBOOT=yes
IPADDR=192.168.100.201 #IP地址
NETMASK=255.255.255.0 #子网掩码
GATEWAY=192.168.100.1 #网关
[root@localhost ~]# systemctl restart network #重启网络服务
[root@localhost ~]# ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.201 netmask 255.255.255.0 broadcast 192.168.100.255 #IP地址配置成功
inet6 fe80::3e1d:31ba:f66a:6f80 prefixlen 64 scopeid 0x20
ether 00:0c:29:95:9b:1b txqueuelen 1000 (Ethernet)
RX packets 10373 bytes 13584878 (12.9 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4285 bytes 277473 (270.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 DR2从：
[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static #dhcp改为static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens33
UUID=3ceed540-b04c-48d6-a4f7-79951f09ea1d
DEVICE=ens33
ONBOOT=yes
IPADDR=192.168.100.202 #IP地址
NETMASK=255.255.255.0 #子网掩码
GATEWAY=192.168.100.1 #网关
[root@localhost ~]# systemctl restart network #重启网络服务
[root@localhost ~]# ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.202 netmask 255.255.255.0 broadcast 192.168.100.255 #IP地址配置成功
inet6 fe80::3e1d:31ba:f66a:6f80 prefixlen 64 scopeid 0x20
inet6 fe80::2558:848e:ba08:4183 prefixlen 64 scopeid 0x20
ether 00:0c:29:27:1c:3f txqueuelen 1000 (Ethernet)
RX packets 10470 bytes 13593710 (12.9 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4240 bytes 273794 (267.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 web1：
[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static #dhcp改为static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens33
UUID=8ecd53ce-afdb-46f8-b7ff-b2f428a3bc8f
DEVICE=ens33
ONBOOT=yes
IPADDR=192.168.100.221 #IP地址
NETMASK=255.255.255.0 #子网掩码
GATEWAY=192.168.100.1 #网关
[root@localhost ~]# systemctl restart network #重启网络服务
[root@localhost ~]# ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.221 netmask 255.255.255.0 broadcast 192.168.100.255 #IP地址配置成功
inet6 fe80::c776:9d00:618:88f2 prefixlen 64 scopeid 0x20
ether 00:0c:29:eb:34:07 txqueuelen 1000 (Ethernet)
RX packets 11508 bytes 14937643 (14.2 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3932 bytes 254623 (248.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 web2：
[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static #dhcp改为static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens33
UUID=09073596-a7cf-404c-a098-28c3ff58c44b
DEVICE=ens33
ONBOOT=yes
IPADDR=192.168.100.222 #IP地址
NETMASK=255.255.255.0 #子网掩码
GATEWAY=192.168.100.1 #网关
[root@localhost ~]# systemctl restart network #重启网络服务
[root@localhost ~]# ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.222 netmask 255.255.255.0 broadcast 192.168.100.255 #IP地址配置成功
inet6 fe80::5134:22f5:842b:5201 prefixlen 64 scopeid 0x20
ether 00:0c:29:0d:f1:75 txqueuelen 1000 (Ethernet)
RX packets 11425 bytes 14931323 (14.2 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4454 bytes 286016 (279.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 4、修改win10系统的IP地址，并关闭防火墙
DR1主服务器配置
1、配置路由转发功能
[root@localhost ~]# vim /etc/sysctl.conf
net.ipv4.ip_forward=1 #配置路由转发功能
#proc响应关闭重定向功能
net.ipv4.conf.all.send_redirects=0
net.ipv4.conf.default.send_redirects=0
net.ipv4.conf.ens33.send_redirects=0
[root@localhost ~]# sysctl -p #加载生效
net.ipv4.ip_forward = 1
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0
[root@localhost ~]# 2、配置虚拟网卡
[root@localhost ~]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp -p ifcfg-ens33 ifcfg-ens33:0 #复制虚拟网卡的配置文件
[root@localhost network-scripts]# vim ifcfg-ens33:0
#添加配置文件信息，原有的信息删除
DEVICE=ens33:0
ONBOOT=yes
IPADDR=192.168.100.10
NETMASK=255.255.255.0
[root@localhost network-scripts]# systemctl restart network #重启网络服务
[root@localhost network-scripts]# ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.201 netmask 255.255.255.0 broadcast 192.168.100.255
inet6 fe80::3e1d:31ba:f66a:6f80 prefixlen 64 scopeid 0x20
ether 00:0c:29:95:9b:1b txqueuelen 1000 (Ethernet)
RX packets 11455 bytes 13700437 (13.0 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4713 bytes 330899 (323.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ens33:0: flags=4163 mtu 1500
inet 192.168.100.10 netmask 255.255.255.0 broadcast 192.168.100.255 #虚拟网卡配置成功
ether 00:0c:29:95:9b:1b txqueuelen 1000 (Ethernet) 3、创建脚本便于service管理
[root@localhost network-scripts]# cd /etc/init.d/
[root@localhost init.d]# vim dr.sh
#!/bin/bash
GW=192.168.100.1 #网关
VIP=192.168.100.10 #虚拟ip
RIP1=192.168.100.221 #真实web1服务器ip
RIP2=192.168.100.222 #真实web2服务器ip
case "$1" in
start)
/sbin/ipvsadm --save > /etc/sysconfig/ipvsadm #保存配置
systemctl start ipvsadm #启动服务
/sbin/ifconfig ens33:0 $VIP broadcast $VIP netmask 255.255.255.255 broadcast $VIP up
#设置ens33:0地址，广播地址，子网掩码，并开启
/sbin/route add -host $VIP dev ens33:0 #添加路由网段信息
/sbin/ipvsadm -A -t $VIP:80 -s rr #指定虚拟服务访问入口，指定轮询算法
/sbin/ipvsadm -a -t $VIP:80 -r $RIP1:80 -g #指定真实服务器web1，dr模式
/sbin/ipvsadm -a -t $VIP:80 -r $RIP2:80 -g #指定真实服务器web2，dr模式
echo "ipvsadm starting ---------------------[ok]"
;;
stop)
/sbin/ipvsadm -C #清空缓存
systemctl stop ipvsadm #关闭服务
ifconfig ens33:0 down #关闭接口
route del $VIP #删除路由信息
echo "ipvsadm stoped--------------------[ok]"
;;
status)
if [ ! -e /var/lock/subsys/ipvsadm ];then #判断文件存在与否决定状态
echo "ipvsadm stoped--------------"
exit 1
else
echo "ipvsadm Runing-----------[ok]"
fi
;;
*)
echo "Usage: $0 {start|stop|status}"
exit 1
esac
exit 0
[root@localhost init.d]# chmod +x dr.sh #给执行权限
[root@localhost init.d]# service dr.sh start #开启服务
ipvsadm starting ---------------------[ok]
[root@localhost init.d]# systemctl stop firewalld.service #关闭防火墙
[root@localhost init.d]# setenforce 0 #关闭增强型安全功能
[root@localhost init.d]# 4、配置DR1服务器keepalived部署
[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# ls
keepalived.conf
[root@localhost keepalived]# vim keepalived.conf
smtp_server 127.0.0.1 #指向本地
router_id LVS_01 #指定名称,备份服务器不同名称
vrrp_instance VI_1 {
state MASTER #主服务器，备份服务器是BACKUP
interface ens33
virtual_router_id 10 #组号相同
priority 100 #优先级，主服务器优先级应大于备份服务器
advert_int 1
authentication {
auth_type PASS #验证类型
auth_pass 1111 #验证密码
}
virtual_ipaddress {
192.168.100.10 #虚拟IP地址
}
}
virtual_server 192.168.100.10 80 { #虚拟服务器
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 192.168.100.221 80 { #真实服务器
weight 1
TCP_CHECK {
connect_port 80 #连接端口
connect_timeout 3 #连接超时
nb_get_retry 3
delay_before_retry 3
}
}
real_server 192.168.100.222 80 { #真实服务器
weight 1
TCP_CHECK {
connect_port 80 #连接端口
connect_timeout 3 #连接超时
nb_get_retry 3
delay_before_retry 3
}
}
}
[root@localhost keepalived]# systemctl start keepalived.service #开启服务
[root@localhost keepalived]# DR2从服务器配置
1、配置路由转发功能
[root@localhost ~]# vim /etc/sysctl.conf
net.ipv4.ip_forward=1 #配置路由转发功能
#proc响应关闭重定向功能
net.ipv4.conf.all.send_redirects=0
net.ipv4.conf.default.send_redirects=0
net.ipv4.conf.ens33.send_redirects=0
[root@localhost ~]# sysctl -p #加载生效
net.ipv4.ip_forward = 1
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0
[root@localhost ~]# 2、配置虚拟网卡
[root@localhost ~]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp -p ifcfg-ens33 ifcfg-ens33:0 #复制虚拟网卡的配置文件
[root@localhost network-scripts]# vim ifcfg-ens33:0
#添加配置文件信息，原有的信息删除
DEVICE=ens33:0
ONBOOT=yes
IPADDR=192.168.100.10
NETMASK=255.255.255.0
[root@localhost network-scripts]# systemctl restart network #重启网络服务
[root@localhost network-scripts]# ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.202 netmask 255.255.255.0 broadcast 192.168.100.255
inet6 fe80::3e1d:31ba:f66a:6f80 prefixlen 64 scopeid 0x20
inet6 fe80::2558:848e:ba08:4183 prefixlen 64 scopeid 0x20
ether 00:0c:29:27:1c:3f txqueuelen 1000 (Ethernet)
RX packets 15720 bytes 14706442 (14.0 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 6289 bytes 1113172 (1.0 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ens33:0: flags=4163 mtu 1500
inet 192.168.100.10 netmask 255.255.255.0 broadcast 192.168.100.255 #虚拟网卡配置成功
ether 00:0c:29:27:1c:3f txqueuelen 1000 (Ethernet) 3、创建脚本便于service管理
[root@localhost network-scripts]# cd /etc/init.d/
[root@localhost init.d]# vim dr.sh
#!/bin/bash
GW=192.168.100.1 #网关
VIP=192.168.100.10 #虚拟ip
RIP1=192.168.100.221 #真实web1服务器ip
RIP2=192.168.100.222 #真实web2服务器ip
case "$1" in
start)
/sbin/ipvsadm --save > /etc/sysconfig/ipvsadm #保存配置
systemctl start ipvsadm #启动服务
/sbin/ifconfig ens33:0 $VIP broadcast $VIP netmask 255.255.255.255 broadcast $VIP up
#设置ens33:0地址，广播地址，子网掩码，并开启
/sbin/route add -host $VIP dev ens33:0 #添加路由网段信息
/sbin/ipvsadm -A -t $VIP:80 -s rr #指定虚拟服务访问入口，指定轮询算法
/sbin/ipvsadm -a -t $VIP:80 -r $RIP1:80 -g #指定真实服务器web1，dr模式
/sbin/ipvsadm -a -t $VIP:80 -r $RIP2:80 -g #指定真实服务器web2，dr模式
echo "ipvsadm starting ---------------------[ok]"
;;
stop)
/sbin/ipvsadm -C #清空缓存
systemctl stop ipvsadm #关闭服务
ifconfig ens33:0 down #关闭接口
route del $VIP #删除路由信息
echo "ipvsadm stoped--------------------[ok]"
;;
status)
if [ ! -e /var/lock/subsys/ipvsadm ];then #判断文件存在与否决定状态
echo "ipvsadm stoped--------------"
exit 1
else
echo "ipvsadm Runing-----------[ok]"
fi
;;
*)
echo "Usage: $0 {start|stop|status}"
exit 1
esac
exit 0
[root@localhost init.d]# chmod +x dr.sh #给执行权限
[root@localhost init.d]# service dr.sh start #开启服务
ipvsadm starting ---------------------[ok]
[root@localhost init.d]# systemctl stop firewalld.service #关闭防火墙
[root@localhost init.d]# setenforce 0 #关闭增强型安全功能
[root@localhost init.d]# 4、配置DR1服务器keepalived部署
[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# ls
keepalived.conf
[root@localhost keepalived]# vim keepalived.conf
smtp_server 127.0.0.1 #指向本地
router_id LVS_02 #指定名称,备份服务器不同名称
vrrp_instance VI_1 {
state BACKUP #备份服务器BACKUP，主服务器是MASTER
interface ens33
virtual_router_id 10 #组号相同
priority 90 #优先级，备份服务器应小于主服务器优先级
advert_int 1
authentication {
auth_type PASS #验证类型
auth_pass 1111 #验证密码
}
virtual_ipaddress {
192.168.100.10 #虚拟IP地址
}
}
virtual_server 192.168.100.10 80 { #虚拟服务器
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 192.168.100.221 80 { #真实服务器
weight 1
TCP_CHECK {
connect_port 80 #连接端口
connect_timeout 3 #连接超时
nb_get_retry 3
delay_before_retry 3
}
}
real_server 192.168.100.222 80 { #真实服务器
weight 1
TCP_CHECK {
connect_port 80 #连接端口
connect_timeout 3 #连接超时
nb_get_retry 3
delay_before_retry 3
}
}
}
[root@localhost keepalived]# systemctl start keepalived.service #开启服务
[root@localhost keepalived]# 配置web1服务器
1、开启并配置httpd服务
[root@localhost ~]# systemctl stop firewalld.service #关闭防火墙
[root@localhost ~]# setenforce 0 #关闭增强型安全功能
[root@localhost ~]# systemctl start httpd.service #开启httpd服务
[root@localhost ~]# cd /var/www/html/
[root@localhost html]# echo "this is abc web" > index.html #创建网站页面
[root@localhost html]# 2、修改回环网卡的虚拟网卡
[root@localhost html]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0 #复制回环网卡配置文件
[root@localhost network-scripts]# vim ifcfg-lo:0
#添加配置文件信息，原有的信息删除
DEVICE=lo:0
IPADDR=192.168.100.10
NETMASK=255.255.255.0
ONBOOT=yes3、添加脚本便于service管理
[root@localhost network-scripts]# cd /etc/init.d/
[root@localhost init.d]# vim web.sh
#!/bin/bash
VIP=192.168.100.10
case "$1" in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
/sbin/route add -host $VIP dev lo:0
echo "1" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" > /proc/sys/net/ipv4/conf/lo/arp_announce
sysctl -p > /dev/null 2>&1
echo "RealServer Start OK "
;;
stop)
ifconfig lo:0 down
route del $VIP /dev/null 2>&1
echo "0" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "0" > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "0" > /proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" > /proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
[root@localhost init.d]# chmod +x web.sh #添加执行权限
[root@localhost init.d]# service web.sh start #开启服务
RealServer Start OK
[root@localhost init.d]# ifup lo:0 #开启网卡
[root@localhost init.d]#ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.221 netmask 255.255.255.0 broadcast 192.168.100.255
inet6 fe80::c776:9d00:618:88f2 prefixlen 64 scopeid 0x20
ether 00:0c:29:eb:34:07 txqueuelen 1000 (Ethernet)
RX packets 13293 bytes 15122368 (14.4 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4692 bytes 360484 (352.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo:0: flags=73 mtu 65536
inet 192.168.100.10 netmask 255.255.255.255
loop txqueuelen 1 (Local Loopback) 配置web2服务器
1、开启并配置httpd服务
[root@localhost ~]# systemctl stop firewalld.service #关闭防火墙
[root@localhost ~]# setenforce 0 #关闭增强型安全功能
[root@localhost ~]# systemctl start httpd.service #开启httpd服务
[root@localhost ~]# cd /var/www/html/
[root@localhost html]# echo "this is xyz web" > index.html #创建网站页面
[root@localhost html]# 2、修改回环网卡的虚拟网卡
[root@localhost html]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0 #复制回环网卡配置文件
[root@localhost network-scripts]# vim ifcfg-lo:0
#添加配置文件信息，原有的信息删除
DEVICE=lo:0
IPADDR=192.168.100.10
NETMASK=255.255.255.0
ONBOOT=yes3、添加脚本便于service管理
[root@localhost network-scripts]# cd /etc/init.d/
[root@localhost init.d]# vim web.sh
#!/bin/bash
VIP=192.168.100.10
case "$1" in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
/sbin/route add -host $VIP dev lo:0
echo "1" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" > /proc/sys/net/ipv4/conf/lo/arp_announce
sysctl -p > /dev/null 2>&1
echo "RealServer Start OK "
;;
stop)
ifconfig lo:0 down
route del $VIP /dev/null 2>&1
echo "0" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "0" > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "0" > /proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" > /proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
[root@localhost init.d]# chmod +x web.sh #添加执行权限
[root@localhost init.d]# service web.sh start #开启服务
RealServer Start OK
[root@localhost init.d]# ifup lo:0 #开启网卡
[root@localhost init.d]#ifconfig #查看网卡信息
ens33: flags=4163 mtu 1500
inet 192.168.100.222 netmask 255.255.255.0 broadcast 192.168.100.255
inet6 fe80::5134:22f5:842b:5201 prefixlen 64 scopeid 0x20
ether 00:0c:29:0d:f1:75 txqueuelen 1000 (Ethernet)
RX packets 16771 bytes 15510870 (14.7 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 7516 bytes 783039 (764.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo:0: flags=73 mtu 65536
inet 192.168.100.10 netmask 255.255.255.255
loop txqueuelen 1 (Local Loopback) 测试群集是否搭建成功
1、用win10测试主机访问虚拟IP地址：192.168.100.10
再次刷新页面，可以测试轮询机制
2、模拟DR1主服务器故障，然后再次用win10测试主机访问虚拟IP地址：192.168.100.10
[root@localhost keepalived]# ifdown ens33:0
#在DR1主服务器上，关闭虚拟网卡，模拟故障
再次刷新页面，可以测试轮询机制
