一.测试拓扑 二.基本配置 1.Win7的一个网卡配置两个网段的IP 2.R1路由器 hostname R1 interface Ethernet0/0 ip address 192.168.10.8 255.255.255.0 no shutdown 3.R2路由器 hostname R2 interface Ethernet0/0 ip address 202.100.1.8 255.255.255.0 no shutdown 三.路由器配置 1.Win7开启路由转发 2.R1配置默认路由或静态路由 ip route 0.0.0.0 0.0.0.0 192.168.10.10 或者 ip route 202.100.1.0 255.255.255.0 192.168.10.10 3.R2配置默认路由或静态路由 ip route 0.0.0.0 0.0.0.0 202.100.1.10 或者 ip route 192.168.1.0 255.255.255.0 202.100.1.10 四.测试 1.因为Win7没有关闭防火墙，所以R1无法ping通Win7的直连地址 R1#ping 202.100.1.10 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 202.100.1.10, timeout is 2 seconds: ..... Success rate is 0 percent (0/5) R1# 2.R1可以ping通R2的地址 R1#ping 202.100.1.8 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 202.100.1.8, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/2 ms R1# 3.如果提前在R2上开启debug，可以看到显示的日志 R2#debug ip icmp ICMP packet debugging is on *Dec 9 02:44:09.989: ICMP: echo reply sent, src 202.100.1.8, dst 192.168.10.8, topology BASE, dscp 0 topoid 0 *Dec 9 02:44:09.989: ICMP: bogus redirect from 202.100.1.10 - for 192.168.10.8 use gw 192.168.10.8 *Dec 9 02:44:09.989: gateway address on different subnet *Dec 9 02:44:09.989: ICMP: echo reply sent, src 202.100.1.8, dst 192.168.10.8, topology BASE, dscp 0 topoid 0 *Dec 9 02:44:09.990: ICMP: echo reply sent, src 202.100.1.8, dst 192.168.10.8, topology BASE, dscp 0 topoid 0 *Dec 9 02:44:09.990: ICMP: echo reply sent, src 202.100.1.8, dst 192.168.10.8, topology BASE, dscp 0 topoid 0 R2# *Dec 9 02:44:09.991: ICMP: echo reply sent, src 202.100.1.8, dst 192.168.10.8, topology BASE, dscp 0 topoid 0 R2# 备注：从日志可以看出，因为数据包从Win7相同网卡进出，所以Win7发出了网络重定向的ICMP包，但是R2收到之后，因为判断地址与自己的地址不在相同网段，所以忽略掉了。