搭建LVS/NAT案例



实验拓扑图：



操作流程：

Director Server :     192.168.4.50 pc50

安装并启用ipvsadm

创建虚拟服务器

向虚拟服务器上加入节点


Real Server :     192.168.4.51 pc51     192.168.4.52 pc52

配置WEB 服务器


Clinet :     192.168.2.253 pc253

连接虚拟服务器测试


具体步骤：

环境准备：

    配置yum源

    # service iptables stop            //关闭防火墙

    # chkconfig iptables off            //关闭开机自启

    # setenforce 0                            //设置SELinux 为宽松模式

    

网站服务器     pc51 /  pc52 ：

    # yum -y install httpd

    [root@pc51 ~]# echo '192.168.4.51' > /var/www/html/test.html

    [root@pc52 ~]# echo "192.168.4.52" > /var/www/html/test.html

    # service httpd start

    # chkconfig httpd on

    # yum -y install elinks

    [root@pc51 ~]# elinks --dump http://localhost/test.html

       192.168.4.51

    [root@pc52 ~]# elinks --dump http://localhost/test.html

       192.168.4.52

    

配置分发器 pc50：

        # mount /dev/cdrom /mnt/

        //安装 ipvsadm   rpm 包在光盘挂载文件下的LoadBalancer目录下

        #cd /mnt/LoadBalancer/

        #yum -y install ipvsadm-1.26-4.el6.x86_64.rpm 

        //开启内核的路由转发功能

        # sed -i '7s/0/1/' /etc/sysctl.conf

        # sed -n '7p' /etc/sysctl.conf 

        net.ipv4.ip_forward = 1


网站服务器 pc51 / pc52 ：

        指定网关地址 192.168.4.50

        # route -n//查看路由

        # route add default gw 192.168.4.50//临时配置网关 网卡重启后生效

        //永久配置网关

        # vim /etc/sysconfig/network-scripts/ifcfg-eth0

        # sed -n '7p' /etc/sysconfig/network-scripts/ifcfg-eth0

        GATEWAY=192.168.4.50

        # ifdown eth0 ; ifup eth0      //重新加载网卡


客户端 192.168.2.253 配置

        指定网关地址 192.168.2.50 ：

        # vim /etc/sysconfig/network-scripts/ifcfg-eth1

        # sed -n '7p' /etc/sysconfig/network-scripts/ifcfg-eth1

        GATEWAY=192.168.2.50

        # ifdown eth1 ; ifup eth1

        # ping -c 2 192.168.4.51

        PING 192.168.4.51 (192.168.4.51) 56(84) bytes of data.

        64 bytes from 192.168.4.51: icmp_seq=1 ttl=63 time=0.322 ms

        64 bytes from 192.168.4.51: icmp_seq=2 ttl=63 time=0.503 ms

        

        --- 192.168.4.51 ping statistics ---

        2 packets transmitted, 2 received, 0% packet loss, time 1000ms

        rtt min/avg/max/mdev = 0.322/0.412/0.503/0.092 ms

        # yum -y install elinks

        


配置分发器 pc50 ：

        # yum -y install ipvsadm-1.26-4.el6.x86_64.rpm

        # rpm -q ipvsadm

        ipvsadm-1.26-4.el6.x86_64

        

添加虚拟服务

        # ipvsadm -L  //查看 IPVS

        IP Virtual Server version 1.2.1 (size=4096)

        Prot LocalAddress:Port Scheduler Flags

          -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

        # ipvsadm -A -t 192.168.2.50:80 -s rr//添加虚拟服务 调度算法为Round Robin

        # ipvsadm -L

        IP Virtual Server version 1.2.1 (size=4096)

        Prot LocalAddress:Port Scheduler Flags

          -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

        TCP  192.168.2.50:http rr

        # ipvsadm -Ln   //- n  数字显示

        IP Virtual Server version 1.2.1 (size=4096)

        Prot LocalAddress:Port Scheduler Flags

          -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

        TCP  192.168.2.50:80 rr

                //向虚拟服务器中加入节点

        # ipvsadm -a -t 192.168.2.50:80 -r 192.168.4.51:80 -m

        # ipvsadm -a -t 192.168.2.50:80 -r 192.168.4.52:80 -m

        # ipvsadm -Ln

        IP Virtual Server version 1.2.1 (size=4096)

        Prot LocalAddress:Port Scheduler Flags

          -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

        TCP  192.168.2.50:80 rr

          -> 192.168.4.51:80              Masq    1      0          0         

          -> 192.168.4.52:80              Masq    1      0          0   

        # /etc/init.d/ipvsadm save//使配置永久生效

        ipvsadm: Saving IPVS table to /etc/sysconfig/ipvsadm:      [确定]

        # cat /etc/sysconfig/ipvsadm

        -A -t 192.168.2.50:80 -s rr

        -a -t 192.168.2.50:80 -r 192.168.4.51:80 -m -w 1

        -a -t 192.168.2.50:80 -r 192.168.4.52:80 -m -w 1

        

客户端测试

        # elinks --dump http://192.168.2.50/test.html

           192.168.4.51

        # elinks --dump http://192.168.2.50/test.html

           192.168.4.52

        //客户端 轮询到不同的后端真实服务器        

        

        [root@pc50 ~]# ipvsadm -Ln --stats

        IP Virtual Server version 1.2.1 (size=4096)

        Prot LocalAddress:Port               Conns   InPkts  OutPkts  InBytes OutBytes

          -> RemoteAddress:Port

        TCP  192.168.2.50:80                 2       10       10      846     1098

          -> 192.168.4.51:80                     1        5        5        423      549

          -> 192.168.4.52:80                     1        5        5        423      549


        模拟pc51 web服务故障：

        [root@pc51 ~]# service httpd stop

        [root@pc50 ~]# ipvsadm -Z

        

         //客户端测试

        # elinks --dump http://192.168.2.50/test.html

           192.168.4.52

        # elinks --dump http://192.168.2.50/test.html

           192.168.4.52

           

        [root@pc50 ~]# ipvsadm -Ln --stats

        IP Virtual Server version 1.2.1 (size=4096)

        Prot LocalAddress:Port               Conns   InPkts  OutPkts  InBytes OutBytes

          -> RemoteAddress:Port

        TCP  192.168.2.50:80                 3       11       11      906     1138

          -> 192.168.4.51:80                     1        1        1         60       40

          -> 192.168.4.52:80                     2       10       10      846     1098

        

        会发现 LVS/NAT 单点故障时 并不能健康性检查

        可以 编写一个脚本 监测两台Real Server 的服务 是否正常 如果监测到故障  将对应的服务在调度服务器 停掉

        使用周期性计划任务 定时运行监测脚本 到达 健康检查的目的