ICMP That InternetControlMessageProtocol, is a network control protocol packets. It is a sub-protocol TCP / IP protocol suite, for passing control messages between IP hosts, routers. Nowhere refers to the network through a control message, whether the host is reachable, a message such as whether the available route network itself. These control messages, while not transmitting user data, but for the transfer of user data plays an important role.
ICMP packets as the data portion of an IP datagram, plus the IP datagram header consisting of datagrams.
From a technical point of view, ICMP is an error detection and reward system, its purpose is to allow us to detect the connection status of the network, but also to ensure the accuracy of the connection.
Its features are:
1. Detection remote host exists;
2. Establish and maintain routing information;
3. redirect data transfer path;
4. Information flow control.