Architectural Milestones

Before proceeding with an actual deployment, there are some significant architectural milestones that must be met first:

• Solutions architecture

• Bill of Materials

• Security posture

Solutions Architecture

You must have a clearly defined architecture and a sound technical design before proceeding with your implementation. This may seem like stating the obvious, but neglecting to clearly define and validate fundamental architectural issues or specific technical designs is common. Do not attempt to learn as you go because the project will lose focus, costs will spiral, and the likelihood of success will decrease dramatically.

Chapter 5 describes the steps in defining a robust, scalable, and enterprise-class architecture in detail.

A Bill of Materials (BOM) is a comprehensive list of the equipment required for any project. One should be produced to avoid delays before you commence the deployment. It is important that you estimate as accurately as possible the specific infrastructure equipment you will require before the deployment begins because this will avoid unnecessary delays during the actual implementation. Remember that you might experience a lag of several weeks when ordering your equipment, depending upon the manufacturer and the size of your WLAN.

As described in Chapter 3, based upon the throughput required to support your applications, the number of users, the estimated number of concurrent users, the floor space to be covered and so on, you should be able to roughly calculate the number of access points you will need. For enterprise deployments, this is most often denoted as a "client to access point ratio"; this could be 10:1, for example, indicating that you would deploy roughly one access point for every ten users.

However, if your plan is to deploy over a long period of time, you may wish to postpone purchasing some of the equipment until the project is underway because this will avoid stockpiling equipment.

Security Posture

It is vital that you have clearly defined your security posture and put in place the required infrastructure to support it before you begin deploying your WLAN. Factors such as the Extensible Authentication Protocol (EAP) mechanism you select will help dictate what authentication, authorization, accounting (AAA) infrastructure you need. If you have chosen to deploy in a geographically dispersed environment, you may need to install additional AAA servers and perhaps even WAN circuits.