When you have collected both the business and the technical requirements from your project, you are ready to start your network design. On rare occasions, you may find yourself building a new network, so you will take these requirements and design an optimal solution to satisfy them. But a more common scenario is that the network already exists in some form, and you are being asked to redesign all or part of it to support new applications or, perhaps, to improve performance. In these cases, you will need to first gather as much information as you can about the existing network so that you can characterize its current operation. This means not only the operation of the network infrastructure, but also the current traffic on it. Keep in mind that your redesign will most likely need to meet or improve performance on existing applications as well as enable any new ones that need to be implemented. So where do you start and what types of information do you need to collect? You want to start by understanding as much as you can about the existing hardware and network layout, both physically and logically.
To Analyze the Network Infrastructure
Start by finding out all the information you can about the equipment and devices on the network. What brands and models of routers and switches are used? What IOS is used? Are there standards that are followed across the network, or is there a mix of equipment and IOS releases? What topology is used in the network?
A good first step is to draw up a network diagram that you feel accurately depicts the layout and topology of the network. This can come from several different sources. In an ideal situation, the team currently managing the network may be able to provide you with fairly accurate diagrams and drawings of what is in place. Of course, you still will want to do enough research to verify their accuracy. If a diagram is not available, is out of date, or is incomplete, you will need to document it yourself. Your book mentions several tools that are commercially available that could help you do this, and you can always resort to Visio. You will want to develop both a logical and a physical view of the network. The logical view will depict the topology and hierarchy of the network, and the physical layout will depict actual locations of equipment and rack elevation diagrams, if possible.
You will first want to complete a high-level diagram that depicts the entire network. To do this, you are going to need geographic information about network locations, information on WAN links between locations, and detailed LAN information, including campus connections between buildings and floors. Once you build the overview diagram, you will want to drill down at each location in order to get more detailed. Here, you want to provide a general, detailed view of the physical and logical layout of the site.
The database server and application server can reside on the same machine but for security and operations they are separate so that if one goes down, the other is still accessible.
This section will explain the staffing requirements for running this type of architecture: what training needs they will have. Explain how you will monitor the system to make sure it runs to its full capacity.
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