> For the complete documentation index, see [llms.txt](https://pshizhsysu.gitbook.io/linux/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://pshizhsysu.gitbook.io/linux/lvs.md).

# LVS

《LVS + Keepalived + DR》

* LVS主机：192.168.2.100
* RS主机 ：192.168.2.104，192.168.2.105
* VIP：192.168.2.110

## LVS主机

### 1、安装ipvsadm

```
$ yum -y install ipvsadm
```

### 2、安装keepalived

```
$ yum -y install keepalived
```

### 3、配置keepalived

编辑`/etc/keepalived/keepalived.conf`文件，内容如下

```
global_defs {
    notification_email {
        acassen@firewall.loc
        failover@firewall.loc
        sysadmin@firewall.loc
    }
    notification_email_from Alexandre.Cassen@firewall.loc
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id LVS_DEVEL
}

vrrp_instance VI_1 {
    state MASTER      #备用服务器上为 BACKUP
    interface eth0    # 网卡
    virtual_router_id 110    # 注意不要和其他keepalived集群冲突
    priority 100      #优先级，数值越大优先级越高；备用服务器上为90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.2.110
    }
}

virtual_server 192.168.2.110 80 {
    delay_loop 6            #(每隔6秒查询realserver状态，是否存活)
    lb_algo wlc                 #(加权轮询算法)
    lb_kind DR                #(DR模式)
    persistence_timeout 0    #(同一IP的连接多少秒内被分配到同一台realserver，0表示不连接)
    protocol TCP             #(用TCP协议检查realserver状态)

    real_server 192.168.2.104 80 {
        weight 100            #(权重)
        TCP_CHECK {
            connect_timeout 10     #(10秒无响应超时)
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80
        }
    }
    real_server 192.168.2.105 80 {
         weight 100
         TCP_CHECK {
             connect_timeout 10
             nb_get_retry 3
             delay_before_retry 3
             connect_port 80
         }
    }
}

virtual_server 192.168.2.110 81 {
    delay_loop 6
    lb_algo wlc
    lb_kind DR
    persistence_timeout 0
    protocol TCP

    real_server 192.168.2.104 81 {
        weight 100
        TCP_CHECK {
            connect_timeout 10
            nb_get_retry 3
            delay_before_retry 3
            connect_port 81
        }
    }
    real_server 192.168.2.105 81 {
         weight 100
         TCP_CHECK {
             connect_timeout 10
             nb_get_retry 3
             delay_before_retry 3
             connect_port 81
         }
    }
}
```

### 4、启动keepalived

```
$ systemctl enable keepalived && systemctl start keepalived
```

## RS主机

编辑`/etc/sysconfig/network-scripts/ifcfg-lo`，内容更改为如下，把lo网卡的IP配置为VIP

```
DEVICE=lo
IPADDR=192.168.2.110
NETMASK=255.255.255.255
BROADCAST=192.168.2.110
ONBOOT=yes
NAME=loopback
```

然后添加路由（实践中发现该步骤不操作也没问题）

```
$ route add -host 192.168.2.110 dev lo
```

修改`/etc/sysctl.conf`，在文件尾部添加如下内容，然后执行命令

```
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_announce = 2
```

然后执行以下命令生效

```
$ sysctl -p
```

## Reference

* <https://www.cnblogs.com/MacoLee/p/5856858.html>
* <https://blog.51cto.com/cuchadanfan/1661576>