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High Availability Network Fundamentals by Chris Oggerino

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Presenting and Describing High Availability Measurements

There are two main ways to state the availability of a network: the percentage method and the defects per million method. Once you understand the basics of these methods, you will understand what you are reading when you get an availability analysis report. Both of these methods use figures like MTBF (Mean Time Between Failure) and MTTR (Mean Time To Repair). The following sections describe these two methods as well as the terms MTBF and MTTR.

The Percentage Method

You have probably heard the term five 9s in relationship to the availability of a network. When someone says this, he or she is really saying that the device or network is 99.999 percent available. In fact, 99.999 percent availability ...

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