Introduction

During the course of a typical day—if there is such a thing as a “typical” day—network consultants are bombarded with questions coming from all directions. These questions come from customers, peers, sales and marketing teams, network administrators, and so on, and the list seems neverending at times. Network consultants, designers, engineers, managers, and so on have developed an instinct over time and sometimes cringe or develop other nervous habits when the phrase, “You got a second?” is uttered.

To the uninitiated, this question seems innocent enough, but after a while they, too, develop the same cringe or nervous habit.

The reason is this: Networks are like snowflakes; no two are alike. This is the challenge that network consultants, engineers, managers, designers, and anyone else involved with a telecommunications network must face every day. The question “You got a second?” is often followed by the question's recipient researching through several volumes, Web sites, old e-mails, rolodexes of contacts, and so on in an effort to find the answer to that seemingly simple question. During this flurry of books, paper, Web sites, phone calls, and voice mails, the questioner sometimes says to himself, “I thought this person knew it all” or “What's the big deal?”

The big deal is that the telecommunications industry is in such a dynamic and fluid state that it is nearly impossible for someone to keep up with everything, leaving many individuals to become Subject Matter Experts, or SMEs, in one or several technologies. This specialization does not relieve the consultant (or whoever was the recipient of the “seemingly simple” question) of the responsibility of knowing something about everything. A “Jack of all trades, master of none” mentality begins to develop.

Not only do network consultants, engineers, managers, and so on face the everyday challenging task of managing and maintaining these networks and answering questions about past, current, or future (proposed) technology, but consultants and others must also document, review, analyze, and find ways to improve these networks. They are often looking for ways to cut costs, while maintaining the same, if not better, level of service to their users. Before a consultant or another can review a network, he must have a clear understanding of the network in question, whether it is a current or planned implementation. Just as no two networks are alike, documentation of such networks follows suit. Often networks are not so much documented as they are drawn—on white boards or with drawing software packages—with little supporting configuration information.

In the course of a single morning, I was the recipient of such questions including, but not limited to the following: Ethernet standards and limitations, Voice over Frame Relay, differences between and history of AMI and B8ZS line coding (and limitations of AMI), FRASI, and review of a customer's network document—and all this before lunch!

One of the questions asked was: “Isn't there a book or Web site that has all of this stuff?” That was the most poignant question of all, and one that caught my attention above all the others.

There was no single resource that I could read through and get what I needed, quickly and easily. Just as there was no single resource that helped me prepare documentation for my customer's current or proposed networks.

This same question further spawned an idea, an idea that was kicked around for a few years that resulted from my suffering through a “typical” day. I began to gather these books, Web sites, and old e-mails. I further created some document templates, and amassed what amounted to a labor of love: a collection of this information that, although organized in a fashion that would make Dewey Decimal cry, was still useful and served as my everyday resource.

What you hold in your hands, and can view on the Internet at www.ciscopress.com/1587050390, is the result of that fateful question “Isn't there a book or Web site that has all of this stuff?”

Purpose of This Book

The purpose of this book is to provide a resource to consultants and engineers to audit (assess), analyze, and evaluate any current or future network environment. Resources include form templates to complete during a network audit, necessary device commands to aid in obtaining necessary information, and consistent forms to aid in documentation.

This book is intended for anyone who designs, manages, sells, administrates, or desires to understand various internetworking technologies, without wading through the sometimes intense discussions, standards documents, books, or white papers involved.

This book is presented as a “greatest hits” of internetworking technologies, augmenting Cisco Press's Internetworking Technologies Handbook: Third Edition, with the addition of insight into some of the technology's infrastructure, as well as documentation templates and analysis guidelines.

How This Book Can Be Used

This book is intended to be used as a resource in whatever fashion the reader sees fit, either as a desktop reference resource or in the field where the tables and calculations help provide near-real time answers to internetworking issues and challenges.

The Twelve Networking Truths

One last note: I invite you to read the following, RFC 1925 by Ross Callon, perhaps ironically published April 1, 1996. Herein are the Twelve Networking Truths. Those in the know will nod silently, smirk, and perhaps chuckle. The uninitiated should consider themselves encouraged and shown the light.

The Twelve Networking Truths

Status of This Memo

This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited.

Abstract

This memo documents the fundamental truths of networking for the Internet community. This memo does not specify a standard, except in the sense that all standards must implicitly follow the fundamental truths.

Acknowledgments

The truths described in this memo result from extensive study over an extended period of time by many people, some of whom did not intend to contribute to this work. The editor merely has collected these truths, and would like to thank the networking community for originally illuminating these truths.

  1. Introduction

    This Request For Comments (RFC) provides information about the fundamental truths underlying all networking. These truths apply to networking in general, and are not limited to TCP/IP, the Internet, or any other subset of the networking community.

  2. The Fundamental Truths

    1. It Has To Work.

    2. No matter how hard you push and no matter what the priority, you can't increase the speed of light.

      • (2A) (corollary). No matter how hard you try, you can't make a baby in much less than 9 months. Trying to speed this up *might* make it slower, but it won't make it happen any quicker.

    3. With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead.

    4. Some things in life can never be fully appreciated nor understood unless experienced firsthand. Some things in networking can never be fully understood by someone who neither builds commercial networking equipment nor runs an operational network.

    5. It is always possible to agglutinate multiple separate problems into a single complex interdependent solution. In most cases, this is a bad idea.

    6. It is easier to move a problem around (for example, by moving the problem to a different part of the overall network architecture) than it is to solve it.

      • (6A) (corollary). It is always possible to add another level of indirection.

    7. It is always something.

      • (7A) (corollary). Good, Fast, Cheap: Pick any two (you can't have all three).

    8. It is more complicated than you think.

    9. For all resources, whatever it is, you need more.

      • (9A) (corollary) Every networking problem always takes longer to solve than it seems like it should.

    10. One size never fits all.

    11. Every old idea will be proposed again with a different name and a different presentation, regardless of whether it works.

      • (11A) (corollary). See rule 6a.

    12. In protocol design, perfection has been reached not when there is nothing left to add, but when there is nothing left to take away.

Feedback

Feedback, as always, is appreciated. This book is intended to be a living volume, with updates and modifications as current standards change and new standards are introduced. The templates herein are designed as a starting point, and I certainly encourage you to use these, create your own, or use some combination of the two. If you find a method or document design that works better than what is presented here and would like to share it, I wholeheartedly encourage you to do so.

I can be contacted either in care of Cisco Press, or directly at .

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