What protocol is icmp?

icmp is the Internet Control Message Protocol, a connectionless-oriented protocol used to transmit error report control information; it is a network layer protocol and is mainly used to transmit control information between hosts and routers. This includes reporting errors, exchanging restricted control and status information, etc.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

ICMP (Internet Control Message Protocol) 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. 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 protocol is a connectionless-oriented protocol used to transmit error reporting control information. It is a very important protocol and it is extremely important for network security. It is a network layer protocol and is mainly used to transfer control information between hosts and routers, including reporting errors, exchanging restricted control and status information, etc. When IP data cannot access the target or the IP router cannot forward data packets at the current transmission rate, ICMP messages will be automatically sent.

ICMP is an important member of the network layer in the TCP/IP model. Together with the IP protocol, ARP protocol, RARP protocol and IGMP protocol, it constitutes the network layer in the TCP/IP model. Ping and tracert are two commonly used network management commands. Ping is used to test network reachability, and tracert is used to display the path to the destination host. Both ping and tracert use the ICMP protocol to implement network functions. They are typical examples of applying network protocols to daily network management.

From a technical perspective, ICMP is an "error detection and reporting mechanism". Its purpose is to allow us to detect the network connection status and ensure the accuracy of the connection. When an accident occurs while the router is processing a data packet, it can report the relevant event to the source of the data packet through ICMP.

Its main functions include: detecting the existence of remote hosts, establishing and maintaining routing data, redirecting data transmission paths (ICMP redirection), and data flow control. During communication, ICMP mainly uses different categories (Type) and codes (Code) to allow machines to identify different connection conditions.

ICMP is a very useful protocol, especially when we need to judge the network connection status.

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