NAT做地址映射，内网服务器ping不通自己的虚拟映射地址是怎么回事

内网电脑192.168.1.2，外网接口20.1.1.1，外网测试pc 20.1.1.2，虚拟地址20.1.1.3

把20.1.1.3映射到192.168.1.2对外访问

现在外网能ping通20.1.1.3

但是内网电脑ping不通20.1.1.3

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in pc

 interface GigabitEthernet0/0 

 port link-mode route 

 combo enable copper 

 ip address 192.168.1.2 255.255.255.0 #

  ip route-static 0.0.0.0 0 192.168.1.1

 [in pc-GigabitEthernet0/0]ping 20.1.1.2 Ping 20.1.1.2 (20.1.1.2): 56 data bytes, press CTRL_C to break 56 bytes from 20.1.1.2: icmp_seq=0 ttl=254 time=1.000 ms 56 bytes from 20.1.1.2: icmp_seq=1 ttl=254 time=1.000 ms 56 bytes from 20.1.1.2: icmp_seq=2 ttl=254 time=1.000 ms 56 bytes from 20.1.1.2: icmp_seq=3 ttl=254 time=1.000 ms 56 bytes from 20.1.1.2: icmp_seq=4 ttl=254 time=1.000 ms

 [in pc-GigabitEthernet0/0]ping 20.1.1.3 Ping 20.1.1.3 (20.1.1.3): 56 data bytes, press CTRL_C to break Request time out Request time out Request time out Request time out Request time out

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router

 interface GigabitEthernet0/0 

 port link-mode route

 combo enable copper 

 ip address 192.168.1.1 255.255.255.0 # 

interface GigabitEthernet0/1 

 port link-mode route 

 combo enable copper

 ip address 20.1.1.1 255.255.255.0 

 nat outbound

 nat server global 20.1.1.3 inside 192.168.1.2 

  ip route-static 0.0.0.0 0 20.1.1.2

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out pc

 interface GigabitEthernet0/1 

 port link-mode route

 combo enable copper

 ip address 20.1.1.2 255.255.255.0 

ping 20.1.1.3 Ping 20.1.1.3 (20.1.1.3): 56 data bytes, press CTRL_C to break 56 bytes from 20.1.1.3: icmp_seq=0 ttl=254 time=2.000 ms 56 bytes from 20.1.1.3: icmp_seq=1 ttl=254 time=1.000 ms 56 bytes from 20.1.1.3: icmp_seq=2 ttl=254 time=2.000 ms 56 bytes from 20.1.1.3: icmp_seq=3 ttl=254 time=1.000 ms 56 bytes from 20.1.1.3: icmp_seq=4 ttl=254 time=1.000 ms