Network Analysis, Architecture & Design, Second Edition
This book works through the processes of analysis, architecture, and design step by step, giving network designers a solid resource for making good design decisions.
TABLE OF CONTENTS Network Analysis, Architecture & Design, Second Edition
3.6: Developing RMA Requirements
3.6 Developing RMA Requirements
Now we will expand on the performance requirements previously discussed, developing and quantifying requirements when possible. In this section, we will discuss two types of thresholds: general and environment specific. General thresholds are those that apply to most or all networks. They are rules of thumb that have been determined via experience to work in most environments. They are applied when there are no environment-specific thresholds to use. Environment-specific thresholds are determined for the environment of the current network project on which you are working. They are specific to that environment and typically are not applicable to other networks. These thresholds are useful in distinguishing between low and high performance for the network.
3.6.1 Reliability
Reliability is a statistical indicator of the frequency of failure of the network and its components and represents the unscheduled outages of service. A measure of reliability is in MTBCF, usually expressed in hours. A related measure is the MTBF, which considers all failures, regardless of their significance at the time of failure, and is a conservative approximation, useful in simple systems. MTBF can confuse the designer of a complex system. As systems become more complex and resource limitations restrict the degree of redundancy or the purchase of higher-reliability components, the use of MTBCF becomes more illuminating, although it does take more careful analysis, focusing on the system performance during specific mission scenarios. MTBF is computed as the inverse of the failure rate, which is estimated through testing...
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