2-R1有默认网关：下一跳 Normal-ARP

3、验证：
（1）命令部署：
R2#debug arp
ARP packet debugging is on
R1#ping 3.3.3.3
（2）抓包验证：
R2#
Mar 1 00:07:26.271: IP ARP: rcvd req src 12.1.1.1 c001.1858.0000, dst 12.1.1.2 FastEthernet0/0
Mar 1 00:07:26.271: IP ARP: sent rep src 12.1.1.2 c002.3430.0000,
dst 12.1.1.1 c001.1858.0000 FastEthernet0/0
R1#show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 12.1.1.1 - c001.1858.0000 ARPA FastEthernet0/0
Internet 12.1.1.2 0 c002.3430.0000 ARPA FastEthernet0/0

Wireshark抓包目的IP不对
4、拓展：
（1）完全清除ARP表
shutdown接口—再no shutdown——clear arp-cache
（2）免费ARP：？

2-R1有默认网关：下一跳 Normal-ARP

原文：http://blog.51cto.com/13856092/2137353