Module 1.0: Introduction

1
Module 1.0 Introduction

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

2
What is a Network?

• Management view
• Technical view

3
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 dont bring money into the organization
• Expense item to the Corporation
• Cannot justify Network based on productivity
  Improvements

4
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?

5
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

6
Traditional Network Design

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

7
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 46 Mbps DS2, DS3, ATM at DS3 rate
8
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
9
Application Bandwidths
Transaction Processing
100 Bytes Few Kbps
Word Processing
100s Kbps Few Mbs
File Transfers
Few Mbps 10s Mbps
Real-Time Imaging
10s Mbps 100s Mbps
10
Networking issues

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

11
Network Design Achievable?
Response Time
Cost
Business Growth
Reliability
12
Where to begin?
TrafficPatterns
Addressing
WWW Access
Campus
Users
Dial in Users
NetworkManagement
Security
WAN
13
A Systems Approach
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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

15
Another Perspective

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

16
One More Look
BusinessPlanning
ImplementNetwork
Network Design
Operations
Develop OperationsPolicies andCapabilities
Define Objectivesand Requirements
DevelopArchitecture
CreateImplementation Plan
Create InitialSolution
Develop DetailedDesign
Procure Resourcesand Facilities
FaultManagement
Define DeploymentStrategy
Create BuildDocumentation
ConfigurationManagement
Stage and Install
ChangeManagement
Review and VerifyDesign
Certify and Hand-offto Operations
Review andApprove
PerformanceManagement
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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

18
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

19
Design and Study of a System
20
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

21
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

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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

23
Conceptual Level of Network Design

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

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Conceptual Level of Network Design

• What do the users want?
• Services
• What do the users need?
• What dont they know they need?
• Organize and Prioritize Requirement

25
Conceptual Level of Network Design

• User Requirements ? Performance Requirements

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

Delay
Reliability
Capacity
26
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 ideas to networking items from
  a design choice standpoint
• Still not at the specific detail level yet

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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

28
Physical Level Network Design

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

29
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

30
Types of Network Design

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

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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

32
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

33
Network Expansion Design

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

34
This Whole Thing is Messy
35
This Whole Thing is Messy

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

36
This Whole Thing is Messy

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

37
This Whole Thing is Messy

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

38
This Whole Thing is Messy

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

39
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

40
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.

10Mb/s Ethernet
10Mb/s Ethernet
T1 1.5Mb/s
41
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