Our last blog looked at the ICMP in more depth and provided an overview into the error messages that are generated by it. In this blog, we can get into more detail with regards to the latter.
The Error Messages That Are Reported By the ICMP
There are four primary error messages that are generated by the IMCP, which are as follows:
1) The Source Quench Error Message:
This is a message generated by the source computer (such as the PDC) to curtail or decrease the flow of network traffic that is being sent to the destination computer. In other words, the PDC is detection that the rate of Data Packet transmission is too high; and thus, needs to slow down in order to ensure that destination computer receives all of the Data Packets that is supposed to get. This is illustrated in the diagram below:
2) The Parameter Problem Message:
The checksum functionality was described in the last section. This is provided in order to provide some level of assurance to the Network Administrator that the ICMP has remained intact. If there are any is mismatch in this alphanumerical that is created, then the integrity of the ICMP cannot be trusted, and thus, it requires further investigation. This is illustrated in the diagram below:
3) The Time Exceeded Error Message:
This is the same as the Time To Live network-based event, as reviewed also in the last section. This is illustrated in the diagram below:
4) The Destination Unreachable Error Message:
This message is generated when a Data Packet cannot reach its final destination for some reason another. For example, there could be hardware failures, port failures, network disconnections, etc. This is illustrated in the diagram below:
5) The Redirection Error Message:
This is when the source computer (such as the PDC) requests that the flow of Data Packets be sent along another route that what was originally planned for. This is very often done in order to optimize and make efficient the network traffic, especially if there is a different way in which the Data Packets can reach their destination in a shorter period of time. This will mean updating the Routing Tables in the associated Routers that are involved. This is illustrated in the diagram below:
Our next blog will review the common applications of the ICMP, and the security vulnerabilities that are associated with it.