User:Howard C. Berkowitz/7deadly

There have been a variety of observations that warn youth of the problems of overindulgence in layering. Many of these observations consider the apparent mystical significance of things with seven parts, such as the Deadly Sins or Snow White's dwarven friends.

The Seven Deadly Layers
Originally presented by Howard C. Berkowitz, when representing the OSI research consortium, the Corporation for Open Systems (COS). At COS, it was axiomatic that OSI was the answer. Unfortunately, COS never definitively stated the question.

Berkowitz's theological explanation
Here is a version of my original writeup, published on USENET. Howard C. Berkowitz 20:51, 13 July 2008 (CDT)

Among the most frequent questions I'm asked in OSI teaching is "do I need to know what all the layers do?" This is especially true of management audiences, who _need_ to know the power centers. They may not know what a layer is, but they know there are seven of them and they don't want a single one to go unsupervised. :-) Over the years, I have found a useful analogy. Educational theory suggests we should start with something that the student knows, and build from there. Therefore, I ask management audiences to reflect not on theoretical network architecture, but on sin.  Specifically, I ask them to consider the Seven Deadly Sins. These sins  have definite relevance to the OSI Reference Model.  The "most popular" deadly sins are analogies for the layers most important for non-developers to know about. Audiences think of sins in a fairly consistent way. Approximately 75% immediately think of Lust. Lust, clearly, relates directly to the Physical Layer.  It is essential to be aware of the function of the Lust Layer, for that defines how to Plug In. Most of the remaining audience splits among Avarice and Gluttony.  These also are important in OSI. Avarice, or Greed, is often realized as the Bottom Line in business. One is closer to understanding the Tao of OSI when one realizes that it places the Bottom Line (i.e., what OSI does for real user applications programs) on Top. The top of the Avarice Layer is the Service Access Point to the Application, or Avarice, Layer. Those members of the audience who thought first of Gluttony also have some understanding of OSI. Gluttony deals with establishing a relationship between a mouth entity and a food entity; Network deals with the next course while Transport deals with the end goal of dessert. Users really need to know the [ISO TR 10000] functions of Application, Transport/Network (as the distinction blurs here), and Physical. International Standardized Profiles follow this model: Application is the visible part of A-, B-, or Avarice Profiles; Transport and Network define T- and U- profiles, and Physical deals with the bottom of T- and U- profiles. These four components also, for instructional purposes, nicely describe the major protocol levels of the Internet Protocol Suite: application protocols, TCP and UDP,IP, and interface protocols. There is always one in the audience, however, who thinks of Sloth. Sloth is a difficult sin. How does one confess it? "Bless me, I have slothed?" "Forgive me for committing sloth? How can I commit not doing something?" Since Sloth is a sin we really have trouble talking about,and involves not doing useful things, it is a relevant analogy to the Session Layer. Both Sloth and Session are needed for theological completeness, but their relevance to the ordinary sinner or the OSI user is fairly limited.
 * Newsgroups: alt.humor.best-of-usenet
 * From: (Eric Henderson)
 * Subject: [comp.protocols.iso] 7 deadly layers of OSI
 * Date: Wed, 4 Aug 1993 23:53:08 GMT
 * From: (Howard C Berkowitz)
 * Subject: FAQ you were afraid to ask
 * Newsgroups: comp.protocols.iso

An alternative theology
As with any theology, there are other explanations, as presented by Harris

Harris' Snow White model
Harris presented an alternative to theology:

Layer Soapboxing...
Howard, I know how you feel about the layer purists, but don't you think this article firmly sets down a soap box and basically preaches about the evils of layering? I just think it seems to me that the article's focus should be more as an overview of the Internet Protocol Suite, and less of a sermon on the evil layering/encapsulation advocates -Eric M Gearhart 03:28, 26 November 2009 (UTC)


 * The section above is intended to be in a subpage, but the IETF, I think, actually does soapbox about layering: RFC 3439 has a section entitled "layering considered harmful." As long as one is stuck on OSI-ish layering rather than functionality (e.g., the end-to-end assumption and its controlled violations, "be conservative in what you send, be liberal in what you acccept", etc.), I honestly don't think one can understand the IPS. Howard C. Berkowitz 03:42, 26 November 2009 (UTC)


 * I think the soapboxing is needed; these are important points and fairly often misunderstood. I don't think much of it belongs in this article, but I don't think it should be hidden away as a signed article or some other sort of sub-article either.


 * I'd like to see most of what Howard has above, plus references to Padlipsky's stuff notably RFC 871, either in Computer networking reference models or in a new article on Internet vs. OSI thinking. Sandy Harris 05:24, 13 March 2010 (UTC)


 * I'm open to suggestions; I'm more frank about it on my user page. Somehow, when dealing with OSI, I feel like I'm trapped in "The Night of the Living Dead" or comparable movie about things that will not die. Seriously, has anyone, outside a teaching environment or people trying to apply it by rote in troubleshooting, used a seven layer model in the last 10 years? Four layer models actually make some sense. If one goes to real-world sublayering and recursion, you can have lots more than seven. Seven is hard.


 * Literally, I have trouble thinking of a real-world stack that has seven layered protocols. Let's see...NFS over XDR over RPC over UDP? Anything else? X.400-1988 stopped using it; X.400-1984 was seven layered. Howard C. Berkowitz 06:18, 13 March 2010 (UTC)