Network Design Considerations

To ensure a network is robust, reliable, and meets the demands of modern communication, several critical attributes need to be considered in the design process. Scalability in network design ensures that a network can efficiently accommodate new users and applications without compromising existing services. Achieving scalability often involves a modular approach, where smaller units or modules are added or removed as needed.

Resilience, conversely, signifies a network's ability to remain highly available and reliable. It facilitates rapid data flow recovery in case of component failures. Effective network resilience is marked by small failure domains, which limit the impact of issues. Redundancy is key in building resilience, applied at multiple levels such as devices, interlinks, software, and processes.

Security and Quality of Service (QoS) are integral to network design. Security measures involve physically safeguarding devices and data, while QoS design controls resource usage during normal and congested network conditions.

The modular design approach effectively addresses scalability and resilience. Modules can be hardware components, building blocks, or functional segments, aiding in the implementation of services and troubleshooting.

Cisco tiered models propose hierarchical network design, dividing networks into discrete layers or tiers with specific functions. This helps optimize network hardware, software, and features, making it applicable to LAN and WAN designs. Examples include the three-tier hierarchical and spine-and-leaf models, as well as the Cisco Enterprise Architecture model that helps in the design of a larger enterprise network.