Internet Control Message Protocol is tightly integrated with IP. ICMP messages, which are delivered in IP packets, are used for out-of-band messages that are related to network operation. Some of ICMP’s functions are to announce network errors, to announce network congestion, to announce timeouts, and to assist in troubleshooting network problems.
ICMP supports an Echo function that sends a packet on a round-trip between two hosts. Ping, which is a common network management tool that is based on the Echo function, transmits a series of packets to measure average round-trip times and to compute loss percentages. Ping is central to the IP Manager ICMP polling.