Once the initial customer requirement, goals, and constraints associated with a proposed network design project have been determined and documented, it’s time to move on to step 2 of the network design process. Identifying and analyzing the current network involves learning as much information as possible about an organization’s existing network. Having this information is absolutely critical, since it provides the designer with in-depth knowledge of the potential issues that will need to be dealt with as part of designing, implementing, and testing the proposed solution.
As a general rule, three main methods are used to identify and analyze a customer’s existing network environment. These include:
- Using existing documentation and interviews with the customer
- Auditing the current network
- Performing network traffic analysis
Each of these methods may be comprised of many steps that involve different processes and applications to gather the required data. Although each method represents a valid and important part of identifying and analyzing an existing network, the actual accuracy of the information varies between the sources. For example, while the information provided through auditing the existing network is likely to be very accurate, information provided by the customer could often be less accurate based on biases and points of view.
The types of information that need to be gathered about the existing network include:
- Network topologies in use at different OSI layers
- Network services currently deployed
- Network configuration including addressing, routing, and equipment configuration
- Network applications in use
- Performance and functionality of the existing infrastructure
The following articles outline each of the methods used to identify and analyze a customer’s existing network, along with an overview of the tools and information sources used by each method.