Network Design and Implementation

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Chapter 14

• Network Design and Implementation

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Network Analysis and Design

• Aspects of network analysis and design
• Understanding the requirements for a
  communications network
• Need to decide how detailed the analysis must be
• Example just install more capacity than needed
  to avoid time consuming estimates of required
  capacity
• Investigating alternative ways for implementing
  the network
• Selecting the most appropriate alternative to
  provide the required capability
• Similar considerations used for voice and data
  networks
• Usually involves a multi-step process

3
Network Implementation

• Process of installing a network and making it
  operational

4
Project Approach

• Network analysis, design and implementation
  usually done in multi-phase project
• Main objective
• Provide network satisfying user requirements at
  an appropriate cost
• May outsource the project
• Usually the case for small businesses

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Network Project Steps

• 1. The request
• 2. Preliminary investigation and feasibility
  study
• 3. Detailed understanding and definition of
  requirements
• 4. Investigation of alternatives
• 5. Network design
• 6. Selection of vendors and equipment
• 7. Calculation of costs
• 8. Documentation of network design and
  implementation plan

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Network Project Steps

• 9. Approval by management
• 10. Equipment order
• 11. Preparation for implementation
• 12. Installation
• 13. Training
• 14. System testing
• 15. Cutover
• 16. Implementation cleanup and audit

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Preliminary Investigation

• A small preliminary project team is formed to
  examine existing communication system
• Determine what improvements are necessary
• Estimate costs and schedule
• Creeping commitment of resources
• Ramp up project personnel and expenditures as
  needed
• Helps minimize financial risk if project is
  stopped

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Project Life Cycle
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Definition of Requirements

• Breakdown requirements by
• Geography
• Traffic loads (peak and average)
• Transaction-based network loads are easier to
  estimate
• Internet-type environments are more difficult to
  estimate due to different traffic types (images,
  sound, video)
• Flow pattern
• i.e. Star vs. mesh
• Traffic in star flows through central node
• Traffic in mesh has more complex pattern
• Response time and reliability

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Definition of Requirements

• Future growth
• Completion date
• Compatibility with old network
• Costs

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Typical Data Network Traffic Load
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Analysis of Expected Traffic Loads
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Investigate Alternatives

• Check availability of different services
• Public switched vs. private lines
• Topology type
• Is packet switching available?
• Satellite?

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Network Design

• Iterative process
• Refinements made as project progresses
• Translate specs to drawings
• Simulate the design
• Allows what if scenarios
• Simulation model can be difficult to create
• Calculate response times
• Example Require transmission of 100 million
  characters in an 8-hour day with no longer than 1
  second response time

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Network Diagram
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Response Time Design Example
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Equipment and Vendor Selection

• Evaluate types of equipment available
• Send out Request
• Request for Quotation (RFQ) to vendors of
  commodity products and services.
• Request for Proposal (RFP) to vendors of custom
  products and services.
• Detail required by vendor in response to RFQ/RFP
  varies based on application
• Evaluate vendor proposals

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Example RFP
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Example Vendor Response to RFP
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Calculate Costs

• Examine costs of alternate designs
• Group costs by
• Circuit costs
• Modem costs
• Other hardware costs
• Software costs
• Personnel costs

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Documentation of Design

• Include
• Specifications
• Software and versions
• Wiring diagrams
• Equipment list

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Management Approval of Design

• Present design and cost/benefit information to
  management
• Design review

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Network Implementation

• Equipment Order
• Make sure equipment specs meet your needs
• Make purchase contingent on acceptance test
  (expensive items)
• Watch out for lead times
• Prepare for Implementation
• Set up network policies
• Modify software
• Track progress

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Network Implementation

• Installation
• Allocate and prepare space
• Mechanical drawings showing locations
• Have vendors install and test equipment
• Make sure equipment interfaces properly
• Training
• Train users, operational and maintenance
  personnel

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Network Implementation

• System Testing
• Perform as much testing as possible initially
• Locate and solve problems
• May need to test hardware and software separately
• Schedule tests when network has minimum load
• Stress test to find network limits
• Workload generator software that produces
  network traffic
• Test component error handling capability
• Failure to test error recovery is a major
  oversight
• Can the network recover?

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Network Implementation

• Cutover
• High visibility event
• Typically scheduled for weekend
• Problems can occur
• Good idea to have technicians from equipment
  vendor companies on hand during cutover
• Implementation Cleanup and Audit
• Make adjustments
• Revise documentation
• Audit
• Find out if benefits of new network are as
  expected
• Interview users and support personnel