Network Design and Implementation IACT 418/918 Autumn 2005 Gene Awyzio SITACS University of Wollongong

2 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

3 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

4 Historical Background Also need to consider –Delay performance –Reliability –Maintainability –Availability

5 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

6 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

7 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

8 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

9 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

10 Architectures & Components of Network Design Requirements Analysis Conceptual: –What is needed from the network –Users’ needs –Applications’ needs –Devices’ needs –Network’s needs

11 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

12 Architectures & Components of Network Design Requirements Analysis Conceptual: –What is needed from the network –Users’ needs –Applications’ needs –Devices’ needs –Network’s needs

13 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

14 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

15 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

16 Component Architecture Addressing/Routing –Address Mechanisms Address classes Subnets Supernets Private and public addressing –Routing Mechanisms Routing Flows Routing Boundaries

17 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

18 Component Architecture Performance Architectures –Quality of Service –Prioritisation, Traffic management, Scheduling, Queueing –Service Level Agreements (SLAs) –Polices

19 Component Architecture Security and Privacy –Threat Analysis –Polices and procedures –Physical security –Protocol and application security –Encryption/decryption –Network perimeter security –Remote access security

20 Selecting Technologies Objectives –To select network technologies for your network design –Using: Requirements Flows Goals Criteria and Guidelines

21 Process Requirements Specification Flow Specification Network Architecture Establishing Design Goals Developing Criteria for Technology Evaluation Making Technology Choices for the Design Guidelines for Selecting Technologies

22 Process Requirements Specification Flow Specification Network Architecture Establishing Design Goals Developing Criteria for Technology Evaluation Making Technology Choices for the Design Guidelines for Selecting Technologies