13 Step Approach to Network Design

2 13 Steps A Systems Approach 8Conduct a feasibility Study 8Prepare a plan 8Understand the current system 8Design the network 8Identify the Geographic scope 8Analyze the Messages 8Calculate Traffic / Circuit Loading 8Develop A control Matrix 8Determine Network configuration 8Software Considerations 8Hardware Considerations 8Network Costs 8Sell and Implement Network

3 1 : Conduct A feasibility Study 8Purpose : Make a go /no go network decision. Do we proceed with designing a new network or come up with another solution? 8What do we do at this Stage? : Define the problem, and put it in writing. 8Deliverable upon completion: Statement of Objectives Feasibility report and/or Oral presentation to Management

4 Analyze Needs Assessment Factors 8Increased volume of inputs/outputs 8Inadequate data processing 8Obsolete Hardware/ Software 8Unsatisfactory Movement of data 8Inadequate file structures (database) 8Inadequate interfacing between application systems and other staff

5 Needs Assessment Factors Continued 8Documentation not available in a timely manner 8Unreliability of current system 8Inability to maintain current system 8Inadequate security/privacy 8Decreasing productivity 8Inadequate training 8Future growth that requires new methods

6 Needs Assessment Factors Continued 8Competition that forces change 8Negative effect of the old system on morale 8New network viewed as positive investment 8Inadequate floor space for personnel files 8Avoidance of future costs 8Need for more timely access to information for improved decision making

7 Needs Assessment Factors Continued 8Increasing flow of information or paperwork 8Need to expand capacity of business functions 8Need to increase level of service quality or performance 8Need for new methods and better exchange of information in conducting international operations 8Reduction of inventories 8Need for a paperless office 8Desire to take advantage of future technology

8 Feasibility Study 8After our problem is defined 1: the scope, boundaries are established 2: preliminary magnitudes of cost identified 3: preliminary geographical study 4: identify areas of business to be affected

9 2: Prepare a Plan 8Consider 1: Technical Feasibility 2: Operational Feasibility 3: Economic Feasibility

10 Prepare a Plan 8STEP 1 : Split Purpose and objectives into three groups of goals 81: Major Goals : reason that network is being built 82: Intermediate Goals : other gains the system can make while serving its major purpose 83: Minor Goals : future enhancements (wish list)

11 Prepare a Plan 8Step 2: Identify Sources of Information and the types of information that need to be collected 8Step 3: Develop some evaluation criteria This aids in doing a post – implementation evaluation. Was our design a success?

12 Evaluation Criteria 8Time 8Cost 8Quality 8Capacity 8Efficiency 8Productivity 8Accuracy 8Flexibility 8Reliability 8Acceptance 8Controls 8Documentation 8Training 8System Life

13 3: Understand the Current System 8Objective: to gain complete understanding of current operations and any system that is functioning 8Understanding of : sequence of operations, processing times, work volumes, current communication systems, existing costs, user management needs/complaints.

14 Understand the Current System 8Gather Information 8Identify application that the network is used for 8Identify proposed future applications 8Learn about industry (check what competitors are doing) 8Legal requirements? 8Who will be affected? 8Try to understand company politics 8Describe and identify each input/ process / output cycle 8Identify file formats

15 Understand The Current System 8Deliverable: Detailed Description of Existing System Should include: design ideas, notes on whether forms or interfaces are adequate, who was helpful, who hindered investigation, impressions, DFD’s etc.

16 4: Design The Network 8At this Stage do not propose solutions just state precisely the requirements such as 8What to do Need to transmit 50 characters per minute plus overhead. As opposed to 9600 bps modem is required.

17 Step 4: Design the new network requirements 8Assemble a list of functions to be performed by the proposed network 8DFD’s would be helpful at this stage 8Review of organizations short term and long term plans Future changes expected etc.

18 8Map out, plan, arrange the parts to satisfy objectives. 8Leave actual hardware and software considerations for later Design The Network

19 5: Identify Geographic Scope 8A data Communication Network has four levels of geographic scope 1: International (worldwide) 2: Country (within boundaries and laws of a single country) 3: City 4: Local facility

20 Identify Geographic Scope 8Start internationally and work your way down 8At International and Country Level all you require is a map 8Illustrate interconnection points etc.

21 Identify Geographic Scope 8At City Level we can consider two things 8State map showing interconnections between cities 8Map showing interconnected local facilities.

22 Identify Geographic Scope 8Local Facility Level Blueprints or drawings of building floor layouts are used 1: Terminal Locations are identified 2: Telephone equipment rooms and location of communication circuits are identified

23 Conclusion step 5 Deliverables at the end of this stage  All maps developed

24 6 : Analyze The Messages 8Can be done in combination with previous Step or post step (calculate traffic/circuit loading) 8Identify each message type that will be transmitted or received 8Identify each message field and average number of characters per field (consider peak or extreme situations) 8In report include description of message and example

25 Analyze The Messages Consider peak periods of the day/ month / financial year Find out size of each message Determine on average how many messages are sent of each type per day as well as originator of messages Use of monitors/analyzers may be helpful Deliverable: Network Link Traffic Table

26 7 Calculate Traffic / Circuit Loading Calculate circuit capacities required at each link on our geographic and location maps Convert characters to bits Examine alternative links possibly to improve speed etc. If links cannot support traffic then make adjustments as needed. Consider time zones etc. Consider Growth factor

27 8: Develop Control Matrix Considers 1: Who uses what? 2: What type of access do they or should they have?

28 Develop Control Matrix Must protect data from threats such as 8Errors and omissions 8Message loss or change 8Disasters 8Breaches of privacy, security/theft 8Unreliability 8Incorrect recovery 8Poor error handling 8Lack of validation For now just state threats and components, our solutions will be developed in next step

29 9: Determine network configurations 8Configuring our network to achieve our goals Generally this step is performed with next two Consider 8Minimum circuit mileage between stations, nodes 8Adequate circuit capacity for future needs 8Reliability 8Efficient software/protocols 8Reasonable cost 8Acceptance by users