Ping command

The picture above shows IA ping B The process of , In the process ：

1. Packet transfer at x When in position ,DestMac=B Left ,SourceMac=Mac_A,Dest ip=Ip_B,Src_ip=Ip_A
2. Packet transfer at y When in position ,DestMac=B Right ,SourceMac=B Left , Dest ip=Ip_B,Src_ip=Ip_A

MAC The address changes when communicating between two devices , During transmission DestMac and SourceMac Will keep changing , however ip The address never changes .

When A equipment ping B Equipment time , Will be sent at the same time arp and icmp agreement .arp The agreement is used according to the purpose ip Get the... Of the default gateway mac Address ,icmp Protocol for implementation ping The function of .