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Module 10 Introduction

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					              Module 1.0: Introduction


•   Network overview
•   What is „network design‟?
•   Network Design Lifecycle
•   How it was done
•   Our approach
•   What is expected or unexpected




K. Salah                        1
                     What is a Network?
•   Management view
•   Technical view




K. Salah                    2
                        Management View
•   A network is a utility
      – Computers and their users are customers of the network utility
•   The network must accommodate the needs of customers
      – As computer usage increases so does the requirements of the
        network utility
•   Resources will be used to manage the network
• The Network Utility is NOT free!
       – Someone must pay the cost of installing and maintaining the
         network
       – Manpower is required to support the network utility
• Utilities don‟t bring money into the organization
       – Expense item to the Corporation
       – Cannot justify Network based on “productivity Improvements”




    K. Salah                       3
                   Management View (cont.)

•    As a network designer, you need to explain to management how the
     network design, even with the higher expense, can save money or
     improve the companies business
       – If users cannot log on to your commerce site, they will try a
          competitors, you have lost sales
       – If you cannot get the information your customers are asking
          about due to a network that is down, they may go to your
          competitor
•    You need to understand how the network assists the company in
     making money and play to that strength when you are developing
     the network design proposal
•    Try to show a direct correlation between the network design project
     and the companies business
       – because you want a faster network is not good enough, the
          question that management sends back is WHY DO I NEED A
          FASTER ONE?



    K. Salah                       4
                                   The Technical View
•   A “Network” really can be thought as of three things and they all need to be considered when working on a
    network design project
       – Connections
       – Communications
       – Services
•   Connection
      – Provided by Hardware that ties things together
              Wire/Fiber Transport Mechanisms
              Routers
              Switches/Hubs
              Computers
•   Communications
      – Provided by Software
      – A common language for 2 systems to communicate with each other
            TCP/IP (Internet/Windows NT)
            IPX / SPX (Novell Netware 4)
            AppleTalk
            Other network OS
•   Services
       – The Heart of Networking
       – Cooperation between 2 or more systems to perform some function - Applications
              telnet
              ftp
              http
              SNMP
              UDP




      K. Salah                                       5
             Traditional Network Design


•    Based on a set of general rules
     – “80/20”
     – “Bridge when you can, route when you must”
     – Can‟t deal with scalability & complexity
•    Focused on capacity planning
     – Throw more bandwidth on the problem
     – No consideration in delay optimisation
     – No guarantee of service quality




K. Salah                           6
               A Look on Multimedia Networking


    Video standard              Bandwidth per user   WAN services




    Digital video interactive   1.2 Mbps             DS1 lines ISDN H11,
                                                     Frame Relay, ATM



    Motion JPEG                 10 to 240 Mbps       ATM 155 or 622 Mbps




    MPEG-1                      1.5 Mbps             DS1 lines ISDN H11,
                                                     Frame Relay, ATM


    MPEG-2                      4~6 Mbps             DS2, DS3, ATM at DS3
                                                     rate




K. Salah                                    7
                         Application characteristics

Applications             Message Length   Msg arrival rate   Delay need   Reliability need




Interactive terminals    Short            Low                Moderate     Very high




File transfer            Very long        Very low           Very low     Very high




Hi-resolution graphics   Very long        Low to moderate    High         Low




Packet-sized voice       Very short       Very High          High         Low




        K. Salah                                8
                     Application Bandwidths



       Transaction
                                     100 Bytes   Few Kbps
       Processing

 Word Processing                     100s Kbps   Few Mbs


    File Transfers                   Few Mbps    10s Mbps



Real-Time Imaging                    10s Mbps    100s Mbps




    K. Salah                  9
                         Networking issues

•    LAN, MAN and WAN
•    Switching and routing
•    Technologies: Ethernet, FDDI, ATM …
•    Mobile networking
•    Internetworking
•    Applications
•    Service quality
•    Security concerns




    K. Salah                       10
             Network Design: Achievable?




      Response Time                    Cost




           Reliability             Business Growth

K. Salah                 11
                      Where to begin?



             WWW               Traffic
                    Addressing
             Access            Patterns

            Campus        Users         Dial in
                                         Users

                                    Network
           Security
                          WAN      Management



K. Salah                    12
              A Systems Approach


                   Flow Analysis

Requirement
  Analysis                             Logical Design



                                       Physical Design

                Routing & Addressing




  K. Salah                13
                A Systems Approach (Cont.)

•   Requirement Analysis is sometimes called “Conceptual” process
•   Routing & Addressing
      – Geographical, Functional
      – Defining Autonomous Systems (AS)
      – Available IP addresses assigned
      – NAT usage
•   Flow Analysis can be part of Logical Design
•   Flow Analysis include:
       – Flow of information from client to server –or- client to client
            For delay calculation
       – Node placement (router, servers, clients)
       – Network Topology (mesh, ring, bus, backbone)
       – Multiplexing of Traffic
       – Prioritized flow or not
            Voice
            Video Conferencing


    K. Salah                             14
                      Another Perspective:

•   Data collection
    – Traffic
    – Costs
    – Constraints
•   Design process
•   Performance analysis
•   Fine tuning
•   A painstaking iterative process




    K. Salah                          15
                         One More Look


  Business            Network                  Implement             Operations
  Planning             Design                   Network
                                                                    Develop Operations
Define Objectives       Develop                    Create
                                                                       Policies and
and Requirements      Architecture           Implementation Plan
                                                                       Capabilities


  Create Initial    Develop Detailed         Procure Resources                 Fault
    Solution            Design                  and Facilities              Management



Define Deployment     Create Build                                          Configuration
                                              Stage and Install
     Strategy        Documentation                                          Management



   Review and       Review and Verify        Certify and Hand-off             Change
    Approve              Design                 to Operations               Management



                                                                            Performance
                                                                            Management




  K. Salah                              16
               Analysis and Design Processes

•      Set and achieve goals
       – Maximising performance
       – Minimising cost
•      Optimisation with trade-offs
       – Recognising trade-offs
       – No single „best‟ answer
•      Hierarchies
       – Provide structure in the network
•      Redundancy
       – Provides availability & reliability




    K. Salah                             17
              Design Study Approaches


•    Heuristic – by using various algorithms
•   Exact – by working out mathematical solutions based on linear
    programming etc., minimising certain cost functions
•   Simulation – often used when no exact analytical form exists.
    Experiments are conducted on simplified models to see the
    performance of network




K. Salah                            18
           Design and Study of a System




K. Salah               19
                        Art or Science?




               The Art of Network Design
                       • Technology choices
                   • Relations to business goals


           The Science of Network Design
               Understanding of network technologies
              Analysis of capacity, redundancy, delay …


K. Salah                        20
            Schema View of Network Design


•   A network design project can be defined on three different levels,
    each with separate outcomes that must come together in the end
      – Conceptual - little details
      – Logical
      – Physical - most details




K. Salah                          21
                              Conceptual


•   User level network requirements
      – Applications
      – Speed
      – Access to Information
•   Management level network requirements
      –    Cost and Budget Limitations
      –    Best Value
      –    Applications to Provide Productivity Improvements
      –    Business Improvement




K. Salah                              22
           Conceptual Level of Network Design

•   Enterprise Level Requirements
      – Centralized / Decentralized Email
•   Area / Department Level Requirements
      – High network bandwidth in medical imaging areas
      – Application Oriented




K. Salah                        23
            Conceptual Level of Network Design

 What do the users want?
     – Services
 What do the users need?
 What don‟t they know they need?

 Organize and Prioritize Requirement




 K. Salah                      24
           Conceptual Level of Network Design

• User Requirements 
      Performance Requirements

           • Timeliness
                                    Delay
           • Interactivity
           • Reliability
           • Quality               Reliability
           • Security
           • Affordability
           • User Numbers
                                            Capacity
           • User Locations
           • User Growth

K. Salah                      25
           Logical Level Network Design


•   Network level requirements based on the conceptual design (the
    big picture)
      – what kind of network will meet the conceptual design based
         on the information gathered
      – Start to get from idea‟s to networking items from a design
         choice standpoint
      – Still not at the specific detail level yet




K. Salah                        26
           Logical Level Network Design


•   Network Protocol selection
     – IP addressing issues
     – Other protocol addressing issues
     – How to make all these protocols work together
•   Need for sub-netting (breaking the network into segments)
•   Network Topology to use
•   Simple block diagram type design




K. Salah                       27
           Physical Level Network Design


•   Hardware level requirements
      – Router performance based on bandwidth requirements
      – Switches, Repeaters, etc...
•   Equipment location requirements
•   Physical security requirements




K. Salah                         28
           Physical Level Network Design


•   Media selection
•   Bandwidth requirements based on conceptual design
•   You design answers the question- Can a network be built using
    the logical level requirements




K. Salah                        29
              Types of Network Design


•   New network design
•   Re-engineering a network design
•   Network expansion design




K. Salah                       30
                   New Network Design


•   Actually starting from scratch
•   No legacy networks to accommodate
•   Major driver is the budget, no compatibility issues to worry about
•   Getting harder to find these situations




K. Salah                             31
           Re-engineering a Network Design


•   Modifications to an existing network to compensate for original
    design problems
•   Sometimes required when networks users change existing
    applications or functionality
•   More of the type of problem seen today




K. Salah                          32
            Network Expansion Design


•   Network designs that expand network capacity
•   Technology upgrades
•   Adding more users or networked equipment




K. Salah                        33
           This Whole Thing is Messy




K. Salah              34
            This Whole Thing is Messy


•   Ambiguous Requirements
     – The network will only transport IP
     – The application requires Novell IPX




K. Salah                       35
            This Whole Thing is Messy


•   Conflicting Requirements
      – Keep costs down
      – High performance cost money




K. Salah                      36
             This Whole Thing is Messy


•   Lack of Design Tools
•   Lack of Management Tools
•   Lack of Vendor Interoperability




K. Salah                          37
             This Whole Thing is Messy


•   Lack of Documentation
      – Existing Network
      – How things should be done. (I.e. wiring)
      – Vendor information




K. Salah                         38
            This Whole Thing is Messy


•   Network Management
      – More management uses more bandwidth
      – Every vendor has their own management tools
      – Vendor tools may conflict with each other




K. Salah                      39
                  This Whole Thing is Messy
   •   Security
         – What is enough security?
         – What is too much security?


           – security and management can not be dealt as
             „afterthoughts‟. It is not an add-on feature, it has to be
             integrated within.


                    Firewall
                    200Kbs

10Mb/s                                                              10Mb/s
                                    T1 1.5Mb/s
Ethernet                                                            Ethernet




    K. Salah                           40
             This Whole Thing is Messy


•   Evolving Network Technologies
      – Everything is a moving target
      – Products are put onto the market before standards are
         approved
      – Whiz Bang Theory
      – Everyone is a computer “expert”




K. Salah                        41

				
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