Chapter 10 Basic Network Design

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Chapter 10Basic Network Design

• BUSI-138

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Systems Development Life CycleSDLC

• Planning
• Analysis
• Design
• Implementation
• Maintenance

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Factors that Affect a Network Design

• Planning should precede equipment purchase
• Nine factors to consider
• Purpose of the network
• Anticipated network traffic
• Redundancy requirements
• User movement
• Future growth
• Security considerations
• WAN connectivity
• LAN and WAN costs
• Existing network topology and resources

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Purpose of the Network

• Number one task match network with user needs
• Scenario bandwidth demand varies with office
• Architects produce drawings saved to large files
• File transmission likely to require high
  bandwidth
• Copywriters generate files with high text content
• Likelihood that files are smaller than
  architects'
• Likelihood that bandwidth need is also less
• General considerations
• What type of information is to be shared?
• What software applications are used?
• What resources are required to run applications?

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Purpose of the Network (continued)

• General considerations (continued)
• What components are to be shared?
• Examples printers, CD arrays, storage, and
  others
• What are the organizational business patterns?
• How are patterns associated with network use?
• What role does the network play in the business?
• What types of computers are to be connected?
• What kinds of LANs and WANs are to interconnect?

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Anticipated Network Traffic

• Two primary factors to consider for a new network
• Number of users
• Types of servers and hosts that will run on
  network
• Scenario 1 home network without a server
• Low network traffic largely consisting of
  Internet sharing
• Scenario 2 home network for entertainment
• Traffic heavier due to use of video
• Scenario 3 office with one server
• Traffic heavier into and out of server
  (bottleneck)
• Scenario 4 office with multiple servers
• Traffic to any one server is light (if tasks
  distributed)

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Anticipated Network Traffic (continued)

• Actions to take when upgrading a network
• Obtain benchmarks of current network use
• Consider traffic from specific devices
• Some benchmarks that can be collected
• Slow, average, peak activity in relation to work
  patterns
• Slow, average, peak activity at different network
  points
• Typical network activity related to certain
  applications
• Example benchmark tracking database server
  activity
• Determines slow, average, peak access times

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Redundancy Requirements

• In relation to network paths
• Provide extra cable and equipment
• Enable system to tolerate failure of one or more
  devices
• Increase redundancy if continuous LAN use
  required
• Include enough network paths to hide malfunction
• User should not be aware of need to reroute
  traffic
• Three examples when down time harms organization
• Users in office cannot access financial programs
• Bank unable to process user and cash transactions
• E-business cannot perform transactions on Web
  server

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User Movement

• Network should adapt to users required to
  relocate
• Business events requiring network to adapt
• Reorganization to meet challenge of changing
  markets
• Restructuring due to merger and/or acquisition
  activity
• Networks should be responsive to physical
  movement
• User may need network access while moving around
• Example user in a hospital or warehouse with
  laptop

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Future Growth

• Successful networks have growth potential
• Scalable networks extend original investment
• Several ways to accommodate growth
• Select 100BaseTX network if goal is 1000BaseTX
• Converts to 1000BaseTX better than 16 Mbps token
  ring
• Design networks around modern routers and
  switches
• Avoid use of older devices, such as bridges and
  hubs
• Install cable of Category 5e or better in cable
  network
• Employ standardized technology in wireless
  networks
• Example use 802.11 devices without proprietary
  add-ons

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Security Considerations

• Security vital in office and home networks
• Levels of protection vary with network
• Examples of security level need by company type
• High payroll-processing company
• Moderate provider of a public database of health
  statistics

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WAN Connectivity

• Varies with design of LANs
• Consider how LAN and WAN will interoperate
• Basic WAN connectivity need
• Use DSL or ISDN lines to connect to Internet
• Complex WAN connectivity based on various needs
• Satellite communications for overseas connections
• Frame relay to join LANs in neighboring states
• T-3 lines for universal access to a Web site used
  to market products

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LAN and WAN Costs

• Important factors in any LAN or WAN project
• Are constrained by budget or specific allocation
• Are projected using itemized list
• Communications cable (for a cabled network)
• Network devices
• Additional computers and printers required for
  network
• Network management/analysis software and hardware
• Installation
• Training
• Vendor consulting
• WAN service or leasing fees

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Existing Network Topology and Resources

• Periodic analysis is needed
• Example 1 inspect cable plant
• Example 2 compile bandwidth utilization baseline
  data
• Example 3 audit resources for usage
• Matters to consider during analysis
• Nature of network traffic
• User demand for additional services
• Challenges of network management
• Demands for greater network reliability and
  redundancy
• Whether existing equipment can be upgraded

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Using Structured Wiring

• Cable fans out as horizontal star from central
  location
• Details of central location
• May be telecommunications room or wiring closet
• Contains one or more switches or routers
• Requirements of structured wiring
• Flexible cabling, such as twisted pair
• Wiring nodes into a physical star
• Adherence to standards for horizontal wiring
• Defined by EIA/TIA-568-A or EIA/TIA-568-B
• Centralizing the cable plant in switches or
  routers

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