Network Design

A Step by Step Process

Design with Change in Mind

• Building the network is just the beginning• Growing the network for larger numbers of

users• Growing the network for more services• Growing the network to include emerging

technologies• It never stops• Design for this from the very beginning

A Design Process

• Identify the uses of the network

• List what happens on what computers

• Client/server or P2P?

• Diagram the network

• Review your plans

• Write a specification

• Build the network

Identify the Uses of the Network• Organisational purpose

– Network is not about technology– Network is to serve a purpose

• Information collecting– Management: core business– Users: on-the-ground issues– Collect, collate, and bring back for review

• Quantifying the Network– # of users, # of machines– Machines per user? Users per machine?– Examples: Pick’n’Pay, UWC, software devel company

What Happens Where?

• Match applications/tasks to specific computers• Rightsize: choose the capabilities of the machines

to match the use requirements• Multiuser computers

– Servers: File, application, database, email, web– Thin-client server

• Single-user computers– Average user, power user– Application suite

Centralisation

• Client/server vs. Peer-to-Peer• Candidates for centralisation

– File services: uniform location– Security: access and permissions– Backup: uniform location

• Configuration Management– Ensuring all machines have the same software and hardware– Why? Easier to fix problems if everything is (supposed to

be) configured the same

• Network Management Software

The Network Diagram

• Logical network diagram– Start with the user – Applications and resources– Pay attention to sharing and security

• Physical network diagram– Machines– Network devices– Physical connectivity

• Combined diagrams– Diagram physical connectivity– Show logical use with descriptive labels

Diagramming Best Practise• Choose appropriate icons/images• Label the icons clearly• List the additional details in small text close to the icons, e.g. machine

name, IP address, etc.• Use conventional methods to depict connectivity, e.g. Token Ring vs

Ethernet• Use colour and styles to denote different types of connectivity

relationships, similar attributes, e.g. OS type, application, etc.• Keep the overall layout simple and within page boundaries• Use space to lay out the contents clearly – keep objects distinct with

space• Resize objects to make best use of space and try to keep size of objects

relative to reality• If using several different colours and/or line types, provide a legend in

an isolated corner• Clearly identify the author(s) and target audience for the diagram

Write out Specification

• Write out a document with everything so far• Why write a document?

– It’s not real until it’s on paper

– Defines the scope of the project (to protect you)

– Tangible item for reference

• Keep it short and clear• Pass around the document for review• Hold a review meeting and revise accordingly

Choose Hardware

• Workstation and server computers

• Network interface cards

• Network devices

• Wiring

• Application software

• Management software

Choose a Vendor• Best to get all the equipment from a single vendor

to avoid “finger pointing”• Collect bids from multiple vendors

– Detailed description of solution– Detailed quote– Rollout plan

• What to look for in a vendor– How frequent they meet with you? How well do the

meetings go?– Do they listen to your needs or push their product?– Can they provide references?– Meet with the techies as well as the salespeople

Build the Network

• Decide how much of the actual building your vendor is going to do

• If the network is very large and complex, or if you are adding services/technologies to an existing network, rather build a staging environment first

• Be sure to pick a time (like a vacation) when no one will be around