One Network LVS-NAT

LVS NAT 模式，VIP 和 RIP 处于同一网段方案，基本架构图如下：

                     ________
                    |        |
                    | client |
                    |________|
                    CIP=192.168.1.254
                        |
                        |
          __________    |
         |          |   |   VIP=192.168.1.110 (eth0:110)
         | director |---|
         |__________|   |   DIP=192.168.1.9 (eth0:9)
                        |
                        |
       ------------------------------------
       |                |                 |
       |                |                 |
RIP1=192.168.1.2   RIP2=192.168.1.3  RIP3=192.168.1.4 (all eth0)
 _____________      _____________     _____________
|             |    |             |   |             |
| realserver  |    | realserver  |   | realserver  |
|_____________|    |_____________|   |_____________|

1. To get a LVS-NAT LVS to work on one network

在调度器上关闭 icmp 包重定向，根据实际情况修改端口，这里为 eth0

director:/etc/lvs# echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
director:/etc/lvs# echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects
director:/etc/lvs# echo 0 > /proc/sys/net/ipv4/conf/eth0/send_redirects

或修改 /etc/sysctl.conf 添加如下选项执行 sysctl -p 使配置永久生效

net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.eth0.send_redirects = 0

设置 diretor 为 RealServer 的唯一包出口（指定 director 为默认网关）

默认设置之后，可能 RealServer 主机路由是以下状态：

realserver:/etc/lvs# route -n
Kernel IP routing table
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
0.0.0.0         192.168.1.9     0.0.0.0         UG        0 0          0 eth0

移除 192.168.1.0/24 的路由，防止 RIP 和 CIP直接通信

realserver:/etc/lvs# route del -net 192.168.1.0 netmask 255.255.255.0 dev eth0
realserver:/etc/lvs# route -n
Kernel IP routing table
0.0.0.0         192.168.1.9     0.0.0.0         UG        0 0          0 eth0

2. Reference

OneNetwork LVS-NAT