What is the ICMP protocol?

ICMP protocol is the Internet Control Message Protocol. It is a subprotocol of the TCP/IP protocol suite and is used to transmit control messages between IP hosts and routers. Although these control messages do not transmit user data, they play an important role in the transmission of user data.

ICMP (Internet Control Message Protocol) is the Internet Control Message Protocol.

It is a sub-protocol of the TCP/IP protocol suite and is used to transmit control messages between IP hosts and routers. Control messages refer to messages about the network itself, such as network connectivity, whether the host is reachable, and whether routes are available. Although these control messages do not transmit user data, they play an important role in the transmission of user data.

ICMP uses the base support of IP as if it were a higher level protocol, however, ICMP is actually an integral part of IP and must be implemented by every IP module.

Working principle:

ICMP provides consistent and easy-to-understand error reporting information. The sent error message is returned to the device that sent the original data, because only the sending device is the logical recipient of the error message. The sending device can then determine the type of error that occurred based on the ICMP message and determine how best to resend the failed packet. But the only function of ICMP is to report problems rather than correct errors. The task of correcting errors is completed by the sender.

We often use the ICMP protocol in the network. For example, we often use the Ping command (available in both Linux and Windows) to check whether the network is accessible. This "Ping" process is actually ICMP. The process of agreement work. There are other network commands such as the Tracert command that trace routes, which are also based on the ICMP protocol.

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