Plan phase

This is the phase where the job of an actual network architect starts. This phase involves getting the right stakeholders together and documenting the network requirements with respect to the network goals, services, user needs, and so on. The plan phase involves identifying the sites, classifying them, and evaluating the existing network infrastructure if any to understand if the existing assets can be reused and redesigned for the new network. This phase also involves finalizing the hardware requirements for the network infrastructure devices.

Some of the questions that need to be answered at this stage are as follows:

• Who are the users of this network and what is the level of segmentation required between the various users?
• What are the services required by each group of users?
• Where are the users located?
• What is the hardware required to meet the user requirements?
• Where will the new hardware be installed?
• What are the power and space requirements at the locations?
• What are the existing services/network if any that need to be integrated/replaced by the new network?
• Where would the network be connected to the internet?
• What is the current security state of the company?
• What operational skills will be required to design/implement and operate the network?

Two important documents that are created during this phase are the Customer Requirement Document (CRD) that contains the detailed technical specifications of the network to be built, and the Site Requirement Specification (SRS) document that contains the physical, electrical, and environmental specifications for each site, where the equipment will be deployed. Site audits are done based upon the SRS documents to ensure that the sites are ready for the equipment to be installed, and any gaps/corrective action required is identified.

We will cover some of these topics in Chapter 2, Networks for Digital Enterprises, where we will describe the network requirements for a modern enterprise.