ICMP (Part 1) – Basic Concept
ICMP stands for Internet Control Message Protocol.
When IP packets send from a computer to a destination computer on the Internet, it needs to travel via a number of gateways. Each gateway on the Internet will send the packets to the next gateway according to the routing table. Actually most data packets will travel successfully to the final destination. However, what if the data packet cannot send to the final destination. Therefore there must be a simple method (protocol) that allow the gateway to inform the sender about the problem. This protocol is called ICMP (Internet Control Message Protocol).