Network Design Asst. Lec.: Estabraq Hazim Page | 1 NETWORK DESIGN METHODOLOGY Top-Down Network Design Methodology Top-down network design is a methodology for designing networks that begins at the upper layers of the OSI reference model before moving to the lower layers. The top-down methodology focuses on applications, sessions, and data transport before the selection of routers, switches, and media that operate at the lower layers. The top-down network design process includes exploring organizational and group structures to find the people for whom the network will provide services and from whom the designer should get valuable information to make the design succeed. Using a Structured Network Design Process The main goal of structured systems analysis is to more accurately represent users’ needs, which unfortunately often are ignored or misrepresented. Another goal is to make the project manageable by dividing it into modules that can be more easily maintained and changed. With large network design projects, modularity is essential. The design should be split functionally to make the project more manageable. Cisco recommends a modular approach with its three-layer hierarchical model. This model divides networks into core, distribution , and access layers .
Network Design Asst. Lec.: Estabraq Hazim Page | 2 System Development Life Cycles network design is divided into four major phases that are carried out in a cyclical fashion: 1. Analyse 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. 2. 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 3. Develop the physical design: During the physical design phase, specific technologies and products that realize the logical design are selected. Also, the investigation into service providers, which began during the logical design phase, must be completed during this phase. 4. 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 your work with a network design proposal. These major phases of network design repeat themselves as user feedback and network monitoring suggest enhancements or the need for new applications. Figure 1-1 shows the network design and implementation cycle.
Network Design Asst. Lec.: Estabraq Hazim Page | 3 Figure 1-1: Network Design and Implementation Cycle Analyzing Business Goals Understanding your customer’s business goals and constraints is a critical aspect of network design. Armed with a thorough analysis of your
- Spring '17
- Ali sadeq