Network requirements and implementation

Case Study 3 – Network requirements and implementation (4 + 3 + 3 = 10 Marks) The first step in defining Reliability Maintainability and Availability (RMA) requirements is to articulate a representative sample of mission scenarios in which the network is going to be used; these are documented in an anecdotal narrative that describes how the usage will occur, when, what is necessary for this mission to succeed, and how important it is to network users. This includes how often, and the level of priority assigned to this mission. For example, the network in one building requires access to data necessary to pay employees that is in another building this data flow path is necessary only from 4 to 5 PM on Friday afternoon so that payroll can be accomplished locally over the weekend and employees are able to be paid on Monday morning. So, this becomes mission-critical during that period and as a fall-back position may continue until the local processing must start or the payroll will not be accomplished on Monday morning, resulting in disgruntled employees and all the unpleasantness that can bring. This path is not mission-critical on Monday afternoon and could Prepared by: Dr Sanjeeb Shrestha Moderated by: Dr Ammar Alazab May, 2020 F5 F6 F7 F8 F9 F10 F11 F12 $ % & 5 6 7 8 9 0
Prepared by: Dr Sanjeeb Shrestha Moderated by: Dr Ammar Alazab May, 2020 MN621 Advanced Network Trimester 1, 2020P age 6 therefore, fail or be shut down for maintenance at that point, provided it doesn’t interfere with other functions. Measuring uptime for a mission-critical network is of utmost importance. The question may be asked in three parts: When should uptime be measured (frequency), where should it be measured, and how should it be measured (service metrics)? First, let’s consider the frequency of measurement. A problem with stating uptime solely as a percentage is that it does not relate a time factor. Consider, for example, a requirement for 99.99% uptime. Without a time factor, that could mean a downtime of 53 minutes per year, 4.4 minutes per month, or 1 minute per week. Without stating a time factor, there could be a single outage of up to 53 minutes. As long as that is the only outage during the year, this availability requirement may be met. Some networks can tolerate a cumulative downtime of 53 minutes per year but may not be able to handle a single downtime of that magnitude. There is a big difference between one large outage and several smaller outages. Stating a time factor (frequency) along with uptime makes that requirement more valid. For networks that cannot tolerate large outages but can tolerate several small outages, 99.99% uptime measured weekly may make more sense than just 99.99% uptime. By stating “measured weekly,” you are forcing the requirement that outages can be no larger than the 1. minute total per week. Source: https://www.nop.edu/read/9074/chapter/8 Answer the following question: 1. In light of this case study justify that networks (or a part of the networks) are subject F5 F6 F F8 F9 F10 F11 F12 Home 5 6 7 8 9 0
Wor CONWETTU wwnloads/MN621%20Advanced%20Network%20Design%20T1%202020.pdf more per year per wrote per week. Without stating a time factor, there could be a single outage of up to 53 minutes. As long as that is the only outage during the year, this availability requirement may be met. Some networks can tolerate a cumulative downtime of 53 minutes per year but may not be able to handle a single downtime of that magnitude. There is a big difference between one large outage and several smaller outages. Stating a time factor (frequency) along with uptime makes that requirement more valid. For networks that cannot tolerate large outages but can tolerate several small outages, 99.99% uptime measured weekly may make more sense than just 99.99% uptime. By stating “measured weekly,” you are forcing the requirement that outages can be no larger than the 1- minute total per week. Source: https://www.nop.edu/read/9074/chapter/8 Answer the following question: 1. In light of this case study justify that networks (or a part of the networks) are subject to mission-critical networks as per the requirements. (4 Marks) 2. “Measurement of the uptime for a network is time-dependent”, illustrate the statement based on the case study. (3 Marks) 3. Analyse why RMA analysis is important for mission-critical networks. (3 Marks) o F ES F6 F7 F8 F9 F10 F11 F12 Home 5 6 7 8

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