ipvsadm --save > /etc/sysconfig/ipvsadm 这个是centos7上执行开启ipvsadm的一个命令，执行完毕之后再执行systemctl start ipvsadm这条命令
yum -y install ipvsadm
vim /etc/sysconfig/network-scripts/ifcfg-lo ifcfg-lo:0
DEVICE=lo:0
IPADDR=10.0.0.200
NETMASK=255.255.255.254
ONBOOT=yes
systemctl restart network
ipvsadm -A -t 10.0.0.200:80 -s rr
ipvsadm -a -t 10.0.0.200:80 -r 10.0.0.42:80 -g
ipvsadm -a -t 10.0.0.200:80 -r 10.0.0.46:80 -g
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/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
route add -host 10.0.0.200 dev lo:0
ip a