一.测试拓扑：

  参照： 据说是12.3(14)T 的IOS才开始有的功能：二.基本配置：A.R1 int e0/0  ip add 192.168.10.1 255.255.255.0  no sh line vty 0 5  password cisco  login ip route 0.0.0.0 0.0.0.0 192.168.10.254B.R2 interface Ethernet0/0  ip address 192.168.10.254 255.255.255.0  no shut interface Ethernet0/1  ip address 202.100.1.2 255.255.255.0  no shutC.R3 interface Ethernet0/0  ip address 202.100.1.3 255.255.255.0  no shut二.R2的NVI配置： int e0/0  ip nat enable int e0/1  ip nat enable access-list 101 permit ip 192.168.10.0 0.0.0.255 any ip nat source list 101 interface e0/1 overload !--动态NVI-NAT Virtual Interface ip nat source static 192.168.10.1 202.100.1.1 extendable !--静态NVI三.测试：A.R3能telnet通R1映射后的公网地址 R3#telnet 202.100.1.1 Trying 202.100.1.1 ... Open User Access Verification Password: R1>show users     Line       User       Host(s)              Idle       Location    0 con 0                idle                 00:01:12   *130 vty 0                idle                 00:00:00 202.100.1.3   Interface    User               Mode         Idle     Peer Address R1>B.R1也能telnet自己的映射后的公网地址 R1#telnet 202.100.1.1 Trying 202.100.1.1 ... Open User Access Verification Password: R1>show users     Line       User       Host(s)              Idle       Location    0 con 0                202.100.1.1          00:00:00 *131 vty 1                idle                 00:00:00 202.100.1.1   Interface    User               Mode         Idle     Peer Address R1> ----可以看到，R1telnet自己的NAT后的公网地址，用的是经过地址转换后的地址C.PC1也能telnet通R1映射后的公网地址 C:\Documents and Settings\Administrator>telnet 202.100.1.1 User Access Verification Password: R1>show users     Line       User       Host(s)              Idle       Location    0 con 0                idle                 00:00:11 *130 vty 0                idle                 00:00:00 202.100.1.2   Interface    User               Mode         Idle     Peer Address R1> ---PC1连接R1 NAT后的公网地址，也用的是经过NAT后的地址