Network Design and Implementation

IACT 918 July 2004

Gene Awyzio

SITACS University of Wollongong

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Historical Background• Traditionally based on developing and

applying a set of rules:– The 80/20 rule [80% local traffic – 20% on the

backbone]

– “bridge when you can, route when you must”

• Such rules were useful when there weren’t many choices in – network technology

– Network services

– Interconnection strategies

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Historical Background

• Network analysis, architecture and design has focused on capacity planning

– The buffer provided by this reduced customer congestion problems

• Bandwidth is only one of the resources that must be considered in network design

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Historical Background

• Also need to consider

– Delay performance

– Reliability

– Maintainability

– Availability

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Network Analysis

• Study of network components

– switches, routers, requirements and performance levels

• … and their inputs and outputs

• To gain an understanding of the networks behaviour under various circumstances

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Network Analysis• Defines and determines:

– Relationships between components

– State of the current network and problems

– Network goals

– Traffic flows

– User and application behaviour• Maps all of these within the network

environment• Allows designers to understand what

problems need to be solved

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Network Architecture

• Uses network analysis data to develop:

– High-level end-to-end structure for network

– Major network functions as architectural components that will be brought together to form the network

• Addressing/routing, network management, performance, security

– Goals for the network

– Interactions, trade-offs, dependencies and constraints

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Design Processes

• Provides physical details to the reference architecture

• Evaluation and choice of technologies• Development of network strategies• Mapping performance and requirements

to design goals • Evaluating designs against goals• Deciding on trade-offs

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Model for Network Design and Implementation Planning• Define the problem to be addressed• Establish and manage customer expectations• Analyse data• Develop set of options for solving problems• Evaluate and optimise options

(including trade-offs)• Selecting one or more options• Planning the implementation

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Architectures & Components of Network Design • Requirements Analysis

• Conceptual:

– What is needed from the network

– Users’ needs

– Applications’ needs

– Devices’ needs

– Network’s needs

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Architectures & Components of Network Design • Requirements Analysis• Process:

– Gathering• Initial Conditions, Expectations

etc

– Developing service metrics

– Characterising behaviour

– RAS requirements

– Delay requirements

– Capacity requirements

– Mapping requirements to Geographic locations

• Requirements map shows location of:

– Devices

– Applications

• From the map we can begin to develop flow specification

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Architectures & Components of Network Design • Requirements Analysis

• Conceptual:

– What is needed from the network

– Users’ needs

– Applications’ needs

– Devices’ needs

– Network’s needs

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Architectures & Components of

Network Design • Flow Analysis• Network designers need to:

– Identify individual & composite flows

– Identify critical flows

– Focus may be on:• Particular applications

• Specific profiles – user, application, criticality

– Develop an Application Flow Map

– Prioritise flows

– Specify Flows any how they need to be managed:

• Best effort

• Predictable Flows

• Guaranteed Flows

Apps E & F

App C

App B

App G

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Flow level & Critical function

• NB: Flows are not necessarily tied to criticality

– Eg: a critical function may only require a best effort flow!

• Must have database server available, but speed of access not critically important

– Eg: a non-critical function may require a guaranteed flow to operate at all!

• A VoIP service between two buildings may require guaranteed flow, but maybe isn’t a critical function

• Critical/non-critical reflects business activity• Flow level reflects network activity

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Architectures & Components of Network Design• The following Architectures need to be considered in

Network design:– Component Architecture for:

• Addressing/Routing

• Network Management

• Performance

• Security

– Reference Architectures for external relationships

– Architectural models for• Topology

• Flows

• Functionality

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Component Architecture

• Addressing/Routing

– Address Mechanisms

• Address classes

• Subnets

• Supernets

• Private and public addressing

– Routing Mechanisms

• Routing Flows

• Routing Boundaries

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Component Architecture

• Network Management architectural considerations:

– In-band/ Out-of-band

– Centralised/distributed/hierarchical

– Scaling of management traffic

– Management of Network management data

• How much, how long, where, storage needs, analysis needs etc

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Component Architecture

• Performance Architectures

– Quality of Service

– Prioritisation, Traffic management,Scheduling, Queueing

– Service Level Agreements (SLAs)

– Polices

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Component Architecture

• Security and Privacy

– Threat Analysis

– Polices and procedures

– Physical security

– Protocol and application security

– Encryption/decryption

– Network perimeter security

– Remote access security

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Selecting Technologies

• Objectives

– To select network technologies for your network design

– Using:

• Requirements

• Flows

• Goals

• Criteria

• and Guidelines

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Process

RequirementsSpecification

FlowSpecification

Network Architecture

Establishing Design Goals

Developing Criteria forTechnology Evaluation

Making Technology Choices for the Design

Guidelines forSelecting Technologies

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Process

RequirementsSpecification

FlowSpecification

Network Architecture

Establishing Design Goals

Developing Criteria forTechnology Evaluation

Making Technology Choices for the Design

Guidelines forSelecting Technologies