request message
host A
host GIP: xxx.xxx.x.145
ARP request
ARP reply
host BIP: xxx.xxx.x.175
host CIP: xxx.xxx.x.177
host FIP: xxx.xxx.x.254
host EIP: xxx.xxx.x.107
who is 177 (target IP)What is 177's MAC
host DIP: xxx.xxx.x.221
I am 177 my MAC address:xx:xx:xx:xx:xx:ed
reply message
