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Top-Down Network Design            Chapter Three   Characterizing the Existing Internetwork       Copyright 2010 Cisco Pre...
What’s the Starting Point?• According to Abraham Lincoln:  – “If we could first know where we are and    whither we are te...
Where Are We?• Characterize the existing internetwork in  terms of:  – Its infrastructure       • Logical structure (modul...
Get a Network Map  Medford                                                                              RoseburgFast Ether...
Characterize Addressing and             Naming• IP addressing for major devices, client  networks, server networks, and so...
Discontiguous Subnets                              Area 0                             Network                           19...
Characterize the Wiring and                Media•   Single-mode fiber•   Multi-mode fiber•   Shielded twisted pair (STP) c...
Campus Network Wiring                         Horizontal        Work-Area                          Wiring            Wirin...
Architectural Constraints• Make sure the following are sufficient  –   Air conditioning  –   Heating  –   Ventilation  –  ...
Architectural Constraints• Make sure there’s space for:  –   Cabling conduits  –   Patch panels  –   Equipment racks  –   ...
Issues for Wireless Installations•   Reflection•   Absorption•   Refraction•   Diffraction
Check the Health of the Existing         Internetwork•   Performance•   Availability•   Bandwidth utilization•   Accuracy•...
Characterize Availability                           Date and Duration   Cause of Last   Fix for Last             MTBF   MT...
Network Utilization in Minute             Intervals                         Network Utilization  16:40:00  16:43:00  16:46...
Network Utilization in Hour               Intervals                                 Network Utilization  13:00:00  14:00:0...
Bandwidth Utilization by                    Protocol             Relative      Absolute                  Multicast        ...
Characterize Packet Sizes
Characterize Response Time          Node A   Node B   Node C   Node D            XNode A                    XNode BNode C ...
Check the Status of MajorRouters, Switches, and Firewalls•   show buffers•   show environment•   show interfaces•   show m...
Tools•   Protocol analyzers•   Multi Router Traffic Grapher (MRTG)•   Remote monitoring (RMON) probes•   Cisco Discovery P...
Summary• Characterize the existing internetwork before  designing enhancements• Helps you verify that a customer’s design ...
Review Questions• What factors will help you decide if the existing  internetwork is in good enough shape to support new  ...
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Chapter03

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Chapter03

  1. 1. Top-Down Network Design Chapter Three Characterizing the Existing Internetwork Copyright 2010 Cisco Press & Priscilla Oppenheimer
  2. 2. What’s the Starting Point?• According to Abraham Lincoln: – “If we could first know where we are and whither we are tending, we could better judge what to do and how to do it.”
  3. 3. Where Are We?• Characterize the existing internetwork in terms of: – Its infrastructure • Logical structure (modularity, hierarchy, topology) • Physical structure – Addressing and naming – Wiring and media – Architectural and environmental constraints – Health
  4. 4. Get a Network Map Medford RoseburgFast Ethernet Fast Ethernet 50 users 30 users Frame Relay Frame Relay CIR = 56 Kbps CIR = 56 Kbps DLCI = 5 DLCI = 4 Gigabit Grants Pass HQ Ethernet Gigabit Grants Pass Ethernet HQ Fast Ethernet 75 users FEP (Front End Processor) IBM Mainframe T1 Web/FTP server Eugene Ethernet T1 Internet 20 users
  5. 5. Characterize Addressing and Naming• IP addressing for major devices, client networks, server networks, and so on• Any addressing oddities, such as discontiguous subnets?• Any strategies for addressing and naming? – For example, sites may be named using airport codes • San Francisco = SFO, Oakland = OAK
  6. 6. Discontiguous Subnets Area 0 Network 192.168.49.0Router A Router B Area 1 Area 2 Subnets 10.108.16.0 - Subnets 10.108.32.0 - 10.108.31.0 10.108.47.0
  7. 7. Characterize the Wiring and Media• Single-mode fiber• Multi-mode fiber• Shielded twisted pair (STP) copper• Unshielded-twisted-pair (UTP) copper• Coaxial cable• Microwave• Laser• Radio• Infra-red
  8. 8. Campus Network Wiring Horizontal Work-Area Wiring Wiring Wallplate Telecommunications Wiring Closet Vertical Wiring(BuildingBackbone) Main Cross-Connect Room Intermediate Cross-Connect Room (or Main Distribution Frame) (or Intermediate Distribution Frame) Campus Building A - Headquarters Backbone Building B
  9. 9. Architectural Constraints• Make sure the following are sufficient – Air conditioning – Heating – Ventilation – Power – Protection from electromagnetic interference – Doors that can lock
  10. 10. Architectural Constraints• Make sure there’s space for: – Cabling conduits – Patch panels – Equipment racks – Work areas for technicians installing and troubleshooting equipment
  11. 11. Issues for Wireless Installations• Reflection• Absorption• Refraction• Diffraction
  12. 12. Check the Health of the Existing Internetwork• Performance• Availability• Bandwidth utilization• Accuracy• Efficiency• Response time• Status of major routers, switches, and firewalls
  13. 13. Characterize Availability Date and Duration Cause of Last Fix for Last MTBF MTTR of Last Major Major Major Downtime Downtime DowntimeEnterpriseSegment 1Segment 2Segment n
  14. 14. Network Utilization in Minute Intervals Network Utilization 16:40:00 16:43:00 16:46:00 16:49:00 16:52:00 16:55:00 Series1Time 16:58:00 17:01:00 17:04:00 17:07:00 17:10:00 0 1 2 3 4 5 6 7 Utilization
  15. 15. Network Utilization in Hour Intervals Network Utilization 13:00:00 14:00:00 15:00:00 Series1Time 16:00:00 17:00:00 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Utilization
  16. 16. Bandwidth Utilization by Protocol Relative Absolute Multicast Broadcast Network Network Rate Rate Utilization UtilizationProtocol 1Protocol 2Protocol 3Protocol n
  17. 17. Characterize Packet Sizes
  18. 18. Characterize Response Time Node A Node B Node C Node D XNode A XNode BNode C XNode D X
  19. 19. Check the Status of MajorRouters, Switches, and Firewalls• show buffers• show environment• show interfaces• show memory• show processes• show running-config• show version
  20. 20. Tools• Protocol analyzers• Multi Router Traffic Grapher (MRTG)• Remote monitoring (RMON) probes• Cisco Discovery Protocol (CDP)• Cisco IOS NetFlow technology• CiscoWorks
  21. 21. Summary• Characterize the existing internetwork before designing enhancements• Helps you verify that a customer’s design goals are realistic• Helps you locate where new equipment will go• Helps you cover yourself if the new network has problems due to unresolved problems in the old network
  22. 22. Review Questions• What factors will help you decide if the existing internetwork is in good enough shape to support new enhancements?• When considering protocol behavior, what is the difference between relative network utilization and absolute network utilization?• Why should you characterize the logical structure of an internetwork and not just the physical structure?• What architectural and environmental factors should you consider for a new wireless installation?

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