Understanding Layers 1, 2, 3: Hubs, Switches, and Routers

Dive into the first three layers of the OSI model—physical, data link, and network—and see how different devices function at each level. You'll explore the roles of hubs, switches, and routers, how they forward or filter traffic, and how attackers exploit weaknesses in these devices. This lecture includes practical comparisons, topology diagrams, and use cases in both enterprise and home networks.

Key topics:

• OSI Layer 1–3 overview

• Hubs vs Switches vs Routers

• MAC addresses, ARP, and IP routing

• Real-world network setups and attack surfaces

• Traffic visibility and control at each layer