When information is transmitted over the Internet, computer systems send and receive data using the Transmission Control Protocol\/Internet Protocol (TCP\/IP) protocol. If there is a connection problem, error, or connection status, messages are sent using ICMP, part of the Internet Protocol.<\/p>\n
When a computer connects to another system over the Internet (such as a home computer connecting to a web server to view a website), it may seem like a quick and easy process. While the connection may take a few seconds, there are often many separate connections that must occur for the computers to communicate with each other successfully. If you were to trace the entire process of connecting to the Internet using the traceroute command, you might be surprised that Internet connections are as successful as they are. This is because for each “hop” along the way, the network must be functional and able to accept requests from your computer.<\/p>\n
In cases of connection problems, ICMP can send return codes to it. Your system will explain why the connection failed.<\/p>\n
These messages may be “Network Unreachable” for a system that is down or “Access Denied” for a secure, password-protected system. ICMP may also provide routing suggestions to help bypass responding systems. While ICMP can send many messages, most of them are never seen by the user. Even if you get an error message, the software you’re using, such as a web browser, has most likely already translated the message into plain (hopefully less technical) language you can understand.<\/p>\n
Internet Control Message Protocol or “Internet Control Message Protocol.”<\/p>\n
The main use of ICMP is to send error reports. When two devices are connected to each other through the Internet. If the data of any of these devices does not reach the destination, ICMP sends the desired error report to the source. For example, if the data sent is too large for a router, the router drops the packet and sends an ICMP message about the dropped data to the source.<\/p>\n
Another use of ICMP is to diagnose and troubleshoot network problems, which is frequently used in the network support process. Common network tools such as ping and traceroute both use the ICMP protocol. The traceroute tool shows the route of the desired information to the destination and the number of routers on the way, the actual physical route of the connected routers that the request must go through before reaching the destination. This command can determine the reason for the delay of the packet sent to the destination.<\/p>\n