This is the talk page for discussing improvements to the Internet Control Message Protocol article. This is not a forum for general discussion of the subject of the article.

Add new text under old text. New to Wikipedia? Welcome! Learn to edit; get help. Start a new topic Assume good faith Be polite and avoid personal attacks Be welcoming to newcomers Seek dispute resolution if needed Article policies Neutral point of view No original research Verifiability

Find sources: Google (books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL

Archives: 1Auto-archiving period: 12 months

This article is rated C-class on Wikipedia's content assessment scale. It is of interest to the following WikiProjects:

Computing: Networking Low‑importance This article is within the scope of WikiProject Computing, a collaborative effort to improve the coverage of computers, computing, and information technology on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.ComputingWikipedia:WikiProject ComputingTemplate:WikiProject ComputingComputing Low This article has been rated as Low-importance on the project's importance scale. This article is supported by Networking task force (assessed as Mid-importance).

The content of ICMP Source Quench was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Redirect Message was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Time Exceeded was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Timestamp was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Timestamp Reply was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Address Mask Request was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Address Mask Reply was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

The content of ICMP Destination Unreachable was merged into Internet Control Message Protocol on 2012-12-20. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page.

In CISCO CCNA Curriculum materials is correct answer for question "At which layer of the OSI model does ICMP operate?" is network layer —Preceding unsigned comment added by 85.70.144.73 (talk) 17:52, 17 March 2008 (UTC)Reply

The lead section of the article recently accumulated some controversial statements on this subject, such as a rewrite of this old paragraph:

ICMP differs in purpose from TCP and UDP in that it is not used to send and receive data between end systems. It is usually not used directly by user network applications, with some notable exceptions being the ping tool and traceroute.

into this paragraph on 3 April 2008:

From a strictly technical perspective, ICMP functions at the transport layer of IP. However, it differs in purpose from other transport protocols such as TCP and UDP in that it is typically not used to ::send and receive data between end systems. It is usually not used directly by user network applications, with some notable exceptions being the ping tool and traceroute. As such, ICMP is often ::considered to be a "network" layer protocol.

and this additional final paragraph on 4 May 2008:

ICMP can "never" be considered a Network Layer protocol. If it were to be considered so, then, it will have to rely on another transport layer protocol to carry its data i.e. Its data will become the payload for a transport layer protocol, as in the case of IP. ICMP is a Transport layer protocol just like TCP and UDP.

A user deleted that contentious paragraph on 5 May 2008, promptly enough, but at the same time amplified the controversial conclusion:

As such, ICMP is commonly (but incorrectly) considered to be a "network" layer protocol.

Now it may be true that some analysts of how the Internet works after the fact have working definitions of "network layer" "Internet layer" and "transport layer" where ICMP fits in the "transport layer" and no other. However, ICMP was part of the Internet layer by definition, when it was built into the Internet. Understanding why it was in that layer would be part of understanding the historical development of the Internet. If what is commonly considered its "layer" has changed, that should be supported with some reference rather than argued originally, or worse, merely asserted.

The company Network Sorcery provides an online guide to Internet protocols [1] that has a simple scheme for classifying protocols into layers that has apparently been favorably received by at least some technical writers and students. Network layer protocols have Ethertype numbers. Transport layer protocols have IP protocol numbers. Application layer protocols have port numbers. Unfortunately, that puts some protocols that have conventionally been considered in the network layer into the transport layer, including ICMP.

According to information, the OSI model has seven layers, then a conventional explanation of the TCP/IP model in terms of five layers developed. Meanwhile, the article Internet protocol suite currently has a chart that provides a nuanced view of only four layers, and historical references to support that view. It puts ICMP in the top of three sublayers in the Internet layer.

The difficulty that some have with this may be that "Internet layer" and "network layer" seem to be synonymous, yet what's in the "Internet layer" may be a matter of history and specific technical implementation, while what's in the "network layer" vs. in the "transport layer" may be a matter of classification according to information systems theory.

--Sonny Moonie (talk) 09:58, 17 May 2008 (UTC)Reply

I think the important point is that the CCNA referes to the OSI modle, but here we refere to the TCP/IP-5-Layer Model. -- AssetBurned (talk) 16:29, 20 May 2008 (UTC)Reply

ICMP is one of the layer 3 Protocol Network layer. Not a transport layer protocol Goodtiming1788 (talk) 04:42, 14 September 2018 (UTC)Reply