Load balancing configuration four LVS / DR mode

1, Environmental ready
to prepare three pure virtual machines, two web servers, and turn off all firewalls and selinux

2, deployment instructions:
• Use NAT network mode
• DR mode requires the Director DIP and all RealServer RIP must be in the same segment and broadcast domains
are designated • All real gateway node gateway

3, LVS-server management software installed lvs

    yum -y install ipvsadm

4, need to generate ipvsadm file manually or start will complain

    [root@vm-2 ~]# ipvsadm --save > /etc/sysconfig/ipvsadm
启动：
    [root@vm-2 ~]# systemctl start ipvsadm

5, configuration ipvsadm:

    [root@vm-2 ~]# ip addr add dev ens33 10.30.161.200:80/32
    设置VIP
    [root@vm-2 ~]# ipvsadm -A -t 10.30.161.200:80 -s rr
    -A添加一个VIP，-t用的是tcp协议，-s rr采用轮训算法
 添加转发到realserverip真实服务器的ip：
    [root@vm-2 ~]# ipvsadm -a -t 10.30.161.200:80 -r 10.30.161.214:80 -g
    [root@vm-2 ~]# ipvsadm -a -t 10.30.161.200:80 -r 10.30.161.241:80 -g
 保存：
    [root@vm-2 ~]# ipvsadm -S > /etc/sysconfig/ipvsadm       
 查看：
    [root@vm-2 ~]# ipvsadm -ln
    [root@vm-2 ~]# ipvsadm -ln --stats
    显示统计信息

6, RS real server configuration

    [root@real-server1 ~]# yum install -y nginx
    [root@real-server1 ~]# echo "real-server1" >> /usr/share/nginx/html/index.html
    两台机器都安装，按顺序添加不同的主机名以示区分
    [root@vm-4 ~]# ip addr add dev lo 10.30.161.200/32   #在lo接口上绑定VIP
    [root@vm-4 ~]# echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
    arp_ignore 设置为1，意味着当别人的arp请求过来的时候，如果接收的设备没有这个ip，就不做出响应(这个ip在lo上，lo不是接收设备的进口)
    [root@vm-4 ~]# echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce #匹配精确ip地址回包
    [root@vm-4 ~]# systemctl start nginx
    [root@vm-4 ~]# systemctl enable nginx

7, test

    curl 10.30.161.200
    [root@localhost ~]# curl 10.30.161.200
    server1
    [root@localhost ~]# curl 10.30.161.200
    server2
            负载均衡实现成功