Chapter 14 Network Design and Implementation

ECET 6302 Stallings: Data & Computer Communications, Chapter 2

*Network Analysis and DesignAspects of network analysis and designUnderstanding the requirements for a communications networkNeed to decide how detailed the analysis must beExample: just install more capacity than needed to avoid time consuming estimates of required capacityInvestigating alternative ways for implementing the networkSelecting the most appropriate alternative to provide the required capabilitySimilar considerations used for voice and data networksUsually involves a multi-step process

*Network ImplementationProcess of installing a network and making it operational

*Project ApproachNetwork analysis, design and implementation usually done in multi-phase projectMain objective:Provide network satisfying user requirements at an appropriate costMay outsource the projectUsually the case for small businesses

*Network Project Steps1.The request2.Preliminary investigation and feasibility study3. Detailed understanding and definition of requirements4.Investigation of alternatives5. Network design6.Selection of vendors and equipment7.Calculation of costs8.Documentation of network design and implementation plan

*Network Project Steps9.Approval by management10. Equipment order11. Preparation for implementation12. Installation13. Training14. System testing15. Cutover16. Implementation cleanup and audit

*Preliminary InvestigationA small preliminary project team is formed to examine existing communication systemDetermine what improvements are necessaryEstimate costs and scheduleCreeping commitment of resourcesRamp up project personnel and expenditures as neededHelps minimize financial risk if project is stopped

*Project Life Cycle

*Definition of RequirementsBreakdown requirements byGeographyTraffic loads (peak and average)Transaction-based network loads are easier to estimateInternet-type environments are more difficult to estimate due to different traffic types (images, sound, video)Flow patterni.e. Star vs. meshTraffic in star flows through central nodeTraffic in mesh has more complex patternResponse time and reliability

*Definition of RequirementsFuture growthCompletion dateCompatibility with old networkCosts

*Typical Data Network Traffic Load

*Analysis of Expected Traffic Loads

*Investigate AlternativesCheck availability of different servicesPublic switched vs. private linesTopology typeIs packet switching available?Satellite?

*Network DesignIterative processRefinements made as project progressesTranslate specs to drawingsSimulate the designAllows what if scenariosSimulation model can be difficult to createCalculate response timesExample: Require transmission of 100 million characters in an 8-hour day with no longer than 1 second response time

*Network Diagram

*Response Time Design Example

*Equipment and Vendor SelectionEvaluate types of equipment availableSend out RequestRequest 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 applicationEvaluate vendor proposals

*Example RFP

*Example Vendor Response to RFP

*Calculate CostsExamine costs of alternate designsGroup costs byCircuit costsModem costsOther hardware costsSoftware costsPersonnel costs

*Documentation of DesignInclude:SpecificationsSoftware and versionsWiring diagramsEquipment list

*Management Approval of DesignPresent design and cost/benefit information to managementDesign review

*Network ImplementationEquipment OrderMake sure equipment specs meet your needsMake purchase contingent on acceptance test (expensive items)Watch out for lead timesPrepare for ImplementationSet up network policiesModify softwareTrack progress

*Network ImplementationInstallationAllocate and prepare spaceMechanical drawings showing locationsHave vendors install and test equipmentMake sure equipment interfaces properlyTrainingTrain users, operational and maintenance personnel

*Network ImplementationSystem TestingPerform as much testing as possible initiallyLocate and solve problemsMay need to test hardware and software separatelySchedule tests when network has minimum loadStress test to find network limitsWorkload generator software that produces network trafficTest component error handling capabilityFailure to test error recovery is a major oversightCan the network recover?

*Network ImplementationCutoverHigh visibility eventTypically scheduled for weekendProblems can occurGood idea to have technicians from equipment vendor companies on hand during cutoverImplementation Cleanup and AuditMake adjustmentsRevise documentationAuditFind out if benefits of new network are as expectedInterview users and support personnel