10 of 11 people found the following review helpful:
5.0 out of 5 stars
A must if you care about your data infrastructure, June 19, 2001
This review is from: High Availability Network Fundamentals (Paperback)
This book provides an excellent model to evaluate the availability of your data network. The tools provided in this book are straight forward and easily understood. If your network is critical to business, and especially if your voice traffic is running over it, you need this book. This book was written as something to use, not just to read.
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6 of 6 people found the following review helpful:
3.0 out of 5 stars
Very elementary introduction to Cisco HA, July 25, 2003
This review is from: High Availability Network Fundamentals (Paperback)
Reliability engineering has been around for quite some time now, and has taken on even more visibility with the rise of the Internet and the subsequent role of eCommerce. The financial stake in reliable networks has driven the need for mathematical analysis that will shed light on how resilient a network is to downtime. This book gives a very elementary introduction to this analysis, and is written for those who do not want to imbed themselves in mathematical constructions beyond the level of elementary algebra. Readers who need a more advanced overview, and one that is more general in not being specific to Cisco products, can consult the references given in the book.
The first chapter of the book introduces the concept of HA, why it is important, and introduces the arithmetic needed to quantify HA, such as the MTBF and the MTTR, the percentage method, and the defects per million method. The author clarifies the difference between MTBF and MTTF, and explains his decision to use MTBF instead of MTTF throughout the book. Due to the level of mathematics to be used in the book, the author does not discuss partial outages in any detail.
Chapter 2 introduces the mathematics to be used in the book to quantify high availability. Eschewing completely the use of calculus in the book, the author sticks to elementary arithmetic and algebra throughout. Many examples are given throughout the chapter on how to compute availability for both the serial and parallel cases. No details of fail-over mechanisms in parallel systems are given since the author wants to stay away from probability theory. N + M redundacy is not discussed in detail as it too is deemed too mathematically complicated.
In the next (very short) chapter serial, parallel, and serial/parallel network topologies are discussed, and an elementary example of how to use "divide-and-conquer" to calculate availability is given.
Chapter 4 overviews the different factors that will affect availability, such as hardware, software, the environment, human factors, and design considerations. The discussion on the prediction of software availability brings in the concept of a "lognormal" distribution from probablity theory, but the author explains it fairly well. Although the discussion on software availability is very elementary, it serves as a good introduction for further reading on the subject. The author is careful to note that the mathematics he is using and the assumptions he is making are geared toward simplifying the mathematics.
In chapter 5, the author gives a more detailed overview of the divide-and-conquer algorithm for calculating availability, restricting his attention to hardware and software failures. He illustrates, with many examples, the construction of reliability block diagrams.
Chapter 6 discusses three "real-world" examples of network availabilty prediction dealing with the uBR924, uBR7246, and 12000 devices. The chapter gives the reader more practice on how to calculate availability using the various components of these devices.
The availability analysis becomes even more useful in chapter 7, where it is done for a small Internet service provider. Use is made of the accompanying CD to the book, which employs Excel spreadsheets to perform the computations and report the results. These results are generalized to a small Enterprise network in chapter 8, and again the author makes use of the CD SHARC spreadsheet to calculate the availability.
The last chapter of the book is an availability analysis of a large voice-over-IP network. All five major contributors to network downtime are considered, and the reader gets a good taste of the complexity involved in analyzing availability in large networks.
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11 of 13 people found the following review helpful:
5.0 out of 5 stars
Unbelievable what this book has in it., September 25, 2002
This review is from: High Availability Network Fundamentals (Paperback)
Sometime when I pick a book to review I have no idea what information is contained within the pages. So much to my surprise I was extremely pleased to find this 240 page book so chock full of useful information.
What I found after reading this book is that the author must be very experienced in the High Availability networking and the information was detailed, but also written at the level for the beginner or intermediate technician.
Taking the reader from the topologies and hardware, to environment and design, the author gives you 10 scenarios from real world situations. Finally there was a cd included with a System High Availability Calculator (SHARC) to calculate reliability and availability.
Overall I have most certainly learned something new from a well organized and well documented book - great job!
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