Protocol icmp

I. purpose of the experiment

1. Master the message format of IP Datagram

two。 Master the calculation method of IP checksum

3. Master subnet mask and route forwarding

4. Understand the meaning of a special IP address

Second, experimental principle

IP (Internet Protocol) is the core protocol in the TCP/IP protocol family, which is responsible for delivering packets from source to destination. All TCP, UDP, ICMP and IGMP data are transmitted in IP Datagram format. IP protocol provides unreliable and connectionless Datagram transmission service, that is, it carries out "best-effort transmission" of data and is only responsible for sending data packets to the destination host, regardless of whether the transmission is correct or not, no verification, no acknowledgement, no guarantee of IP packet arrival order, and the problem of error correction retransmission is handed over to the transport layer to solve.