Analyze requirements. In this phase, the network analyst interviews
users and technical personnel to gain an understanding of the business and technical goals
for a new or enhanced system. The task of characterizing the existing network, including the
logical and physical topology and network performance, follows. The last step in this phase
is to analyze current and future network traffic, including traffic flow and load, protocol
behavior, and quality of service (QoS) requirements.
Develop the logical design. This phase deals with a logical topology for the new
or enhanced network, network layer addressing, naming, and switching and routing protocols.
Logical design also includes security planning, network management design, and the initial
investigation into which service providers can meet WAN and remote access requirements.
Develop the physical design. During the physical design phase, specific technologies
and products to realize the logical design are selected. Also, the investigation into service providers,
which begin during the logical design phase, must be completed during this phase.
Test, optimize, and document the design. The final steps in top-down network design are to
write and implement a test plan, build a prototype or pilot, optimize the network design, and document
our work with a network design proposal.