2.2. Network Devices and Their Functions

💡 First Principle: Different network problems require different devices. The OSI layer a device operates at determines what problem it solves—hubs repeat signals (Layer 1), switches forward frames (Layer 2), routers forward packets (Layer 3).

What breaks without proper device selection? Put a hub where you need a switch, and every device sees everyone else's traffic—a security disaster and performance nightmare. Use only switches in a multi-subnet environment, and subnets become isolated islands—nothing routes packets between them.

Think of mail delivery: a hub is a bullhorn (everyone hears everything), a switch is an office mailroom (knows which desk gets which mail), and a router is the postal service (delivers between cities).