Network Design, Scaling, and Redundancy
Design Principles
Scalability
A scalable network can support more users, devices, and traffic without redesigning everything from scratch. Good design separates access, distribution, and core functions.
Redundancy
Redundancy improves availability by providing alternate devices, links, and paths so a single failure does not stop service.
Hierarchy
Hierarchical design reduces complexity by giving each layer a clear role. Access layers connect endpoints, distribution layers aggregate and filter, and core layers move traffic quickly.
Design goals and mechanisms
| Goal | Mechanism |
|---|---|
| Availability | Redundant links and devices |
| Performance | Proper capacity planning and QoS |
| Security | Segmentation and access control |
| Manageability | Hierarchy and standardization |
What is a major benefit of network redundancy?
Redundant designs improve uptime by preserving connectivity during failures.
Correct answer: It provides alternate paths if a component fails
Why is hierarchical design useful in large networks?
Clear roles for access, distribution, and core layers make networks easier to manage.
Correct answer: It limits complexity and makes expansion and troubleshooting easier
Single point of failure vs redundancy
Single point of failure
- One failure can stop service
- Simpler and cheaper initially
- Riskier for critical infrastructure
Redundant design
- Alternate paths improve resilience
- More cost and complexity
- Better for important services
Which design choice most directly improves availability?
Redundant connectivity can keep traffic flowing when one link fails.
Correct answer: Adding a redundant uplink