1.1-PC1无默认网关/Proxy-ARP（代理ARP）

Posted 2020-12-02

1、实验拓扑：

2、命令部署：
PC1(config)#no ip default-gateway 12.1.1.2
拓展：PC1(config)#default int int f0/0

3、验证：
（1）默认开启代理：
R2#debug arp
ARP packet debugging is on
PC1#ping 3.3.3.3

R2#
Mar 1 00:16:17.167: IP ARP: rcvd req src 12.1.1.1 c001.1858.0000, dst 3.3.3.3 FastEthernet0/0
Mar 1 00:16:17.171: IP ARP: creating entry for IP address: 12.1.1.1, hw: c001.1858.0000
*Mar 1 00:16:17.171: IP ARP: sent rep src 3.3.3.3 c002.3430.0000,
dst 12.1.1.1 c001.1858.0000 FastEthernet0/0
注意：可以看到3.3.3.3对应的MAC是：c002.3430.0000，这是R2 f0/0的接口MAC地址。
证明：此过程是Proxy-ARP

PC1#show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 3.3.3.3 3 c002.3430.0000 ARPA FastEthernet0/0
Internet 12.1.1.1 - c001.1858.0000 ARPA FastEthernet0/0

（2）关闭代理功能：
R2(config)#int f0/0
R2(config-if)#no ip proxy-arp

PC1#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

R2#
*Mar 1 00:56:05.231: IP ARP: rcvd req src 12.1.1.1 c001.1858.0000, dst 3.3.3.3 FastEthernet0/0