3.2. Network Infrastructure

💡 First Principle: To design and troubleshoot a network, you must understand the specific role of each hardware device in the stack, from the modem connecting to the ISP to the switch connecting local devices.

Scenario: A small business's internet connection is down. Your diagnostic path is to first check the modem's status lights to confirm a connection with the ISP, then check the router to see if it's routing traffic, and finally check the switch to ensure local devices are communicating.

A network is built from a collection of specialized hardware devices, each performing a distinct function.

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⚠️ Common Pitfall: Using a switch where a router is needed. A switch operates at Layer 2 and connects devices on the same network. A router operates at Layer 3 and connects different networks (like your local network and the internet).

Key Trade-Offs:

• Managed vs. Unmanaged Switch: An unmanaged switch is a simple plug-and-play device. A managed switch offers advanced features like VLANs, port security, and traffic monitoring, but requires configuration and is more expensive.

Reflection Question: In a typical SOHO network, what are the distinct roles of the modem, the router, and the switch in getting a packet from your PC to a website on the internet?