Introduction to ICMP – Part 2

Our last blog provided an overview into the Internet Protocol Suite, as well as the ICMP.  In this blog, we do a deeper dive into the ICMP, and provide a high-level view of the error messages that are reported with it.

A Technical Review of the ICMP

From a historical perspective, there have been different versions of the IMCP.  It was created and established by Jon Postel, who has been credited with playing a fundamental role in the implementation of the Internet as we know it today.  The first ICMP standard was formulated in April of 1981 and was originally published in the RFC 777.

After that, the ICMP has been through several iterations, and the one that is being used today has made its appearance in RFC 792, and that can be seen here by clicking on this link.  This version of the ICMP has also been published by the Internet Engineering Task Force in September 1981 as well.

Because the ICMP technically resides at the Internet Layer, it is carried by the IP Packets, and not the Data Packets that transmit the information and data from the source to the destination.   The ICMP messages are sent via the use of what are known as “Datagrams”, and more information about what that specifically is can be seen here at this link.

The Datagram contains an IP Header that entirely covers or encapsulates the error message that resides in the ICMP.  It is important to note that the error messages contained in the ICMP also contains the IP Header from the Data Packet that was unable to reach its final destination.  Going to back to our previous example, because of this functionality, the PDC will thus know the Data Packet that could not be delivered.

When the ICMP is used in IPv4 or IPv6, the ICMP shows up after the IP Packet Headers of these two protocols.  The ICMP is specifically identified as “Protocol Number 1”, and is broken down in the following order:

1)     The IPv4/IPv6 Packet Header;

2)     A three field ICMP Header which consists of the following:

  • The code that identifies the specific error message;
  • A “minor code” that contains more information about the error message;
  • A checksum that allows for the Network Administrator to check for the integrity of the ICMP.  A checksum is simply a sequence of alphanumeric characters.  The Network Administrator uses this functionality in order to make sure that there are no intentional or unintentional alterations made to the ICMP.

3)     The original Data Packet Header which failed delivery; typically, this is about 8 bytes worth of information/data payload.

This is illustrated in the diagram below:

Ethernet Packet
Ethernet Packet

The following matrix examines the codes and their corresponding messages and other pieces of information/data that are generated by the ICMP:

Error Codes and Messages

It is important to note at this point that one of the events that launches an ICMP is known as the “Time to Live”, (also known as “TTL” for short).  This metric represents the maximum number of Routers that a Data Packet can be sent through and is numerically decreased by a value of 1 each time the Data Packet is processed by a specific Router.  If for some reason the TTL value falls down to zero, the Data Packet is then dropped from the network flow and is reported back to the PDC.

Just because a Data Packet was dropped from the network flow because of a TTL, this does not mean that the Data Packet by itself is malformed in any way, or that there are any problems with Router(s) that is (are) being used.  The TTL was created in an effort to reduce backlog in network traffic, and to make sure that the network flow remains consistent and efficient.


Our next blog will examine these error messages in greater detail, and why it is important for the Network Administrator to thoroughly understand them.


1)     https://erg.abdn.ac.uk/users/gorry/eg3567/inet-pages/icmp.html

30 thoughts on “The Internet Control Message Protocol (ICMP) – Part 2

  1. This information is as good as anything one would get from any IT consulting. Thanks so much for making it available for free.

  2. ICMP as an IT service is very important in helping network administrators identify errors in the network. I’ve learnt a lot from the post.

  3. I like how technical and detail this write-up is. Non computer based companies can best implement such systems into their infrastructure through IT outsourcing.

  4. The information presented here would be very helpful for any computer company looking to understand its operations in detail. I’m very grateful for the informative piece 🙂

  5. This article entails very detailed information that every compiter company must know. It is entirely a big help to further understand IT service.

  6. Thanks for elaborating this for us. Another reason why I respect IT Support people. This is not as easy as it looks. Despite of dealing with just codes.

  7. Datagrams and error analyses definitely come in handy when sending information across servers and different geographical locations. Once again, Be Structured proves to be the best IT Service in data implementation with its ICMP surveillance reports and network technology.

  8. Thank you very much for the informative article! IT Consulting is a must when it comes to internet security. You need to consult the experts about this.

  9. Thanks for the derailed information although I must confess,the write up us full of technical terms..a layman cannot understand the write up.. Your IT Services are topnotch and you should make your articles easier to comprehend

  10. You are really a good IT Support system. Programmers and network administrators will really find this valuable. I’m learning too and it really worthwhile knowing these all.

  11. Though I am a Computer science student. There is no day I don’t gain from Los Angeles Computer Company and the articles they post. Thanks so much and please Keep this good job working

  12. I quite like how technical and detailed this article is. It’s even better than having an IT consulting exercise.

  13. Given how complicated ICMP is I think the best route to go with it is IT outsourcing. Technical matters are always best left to the industry professionals.

  14. As a member of an IT support team I find this write-up super informative and helpful. I can’t thank you enough for sharing 🙂

  15. ICMP protocols are one of those IT services that have really revolutionized data transmission efficiency. Many thanks for the great article. Keep it up.

  16. Any computer company should find this treasure trove of information absolutely vital. Having an idea of how various network protocols work can be very helpful in helping maintain a good and secure network.

  17. This is the most valuable information on ICMP from the most inspirational Los Angeles Computer Company. I hope it really helps those that needed the information most.

  18. This is the kind of information that every IT support structure should be privy to. Thanks a lot for making it available!

  19. I’m of the opinion that IT outsourcing is the best way to implement an ICMP protocol. That way one is not prune to many errors.

  20. Are there any companies that offer IT services that involve ICMP? That would be very convenient for many organizations.

  21. Any computer company that doesn’t have measure such as ICMP for their network is definitely not operating at its fullest potential. It’s a very helpful tool to have.

  22. This article was very informative, thanks for sharing, hope you can keep growing as a successful company and become in the best Los Angeles Managed Service Providers

  23. This is where the importance of Los Angeles Managed Service Providers or any brand that provides this services really shines. As a previous comment stated even if these are just codes it can make or break a system.

  24. The failed delivery messages and ICMP protocol systems are brilliant!! It’s interesting to see how ICMP has evolved over the years and how Be Structured has utilized its prowess as a Los Angeles IT Service. Thanks for sharing.

  25. Thanks BeStructured and the IT support Los Angeles for their educative post. This post makes it clear for the importance of Network Administrator in various company….Thanks for sharing!💯

  26. Be Structured is the best computer company that is always updating its client on the latest trends and threat i the IT world. Great information you have provided here.

  27. This tyle of article educates us about different IT service. terms that we should all be aware of. I hope you continue. to write up articles like this.

Leave a Reply

Your email address will not be published. Required fields are marked *