Everything that happens at Layer 2 inside a building.
Walk through how a switch builds its MAC table, how 802.1Q tags carry many VLANs over a single trunk, why Spanning-Tree exists, how EtherChannel bundles links, and how 802.11 wireless fits into the wired LAN.
Welcome to module 3. Everything that happens at Layer 2 inside a building. I'll meet you again at the top of every chapter — this module's course coverage is 18%, so don't rush it. Pick chapter 3.1 below to start.
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An L2 switch makes forwarding decisions by destination MAC. It builds its table from source MACs of arriving frames. This chapter walks through MAC learning, flooding, and the difference between a hub, switch, and router.
A VLAN is a separate broadcast domain inside one physical switch. Access ports belong to one VLAN and carry untagged traffic for the connected host. This chapter teaches access-port configuration and verification.
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A trunk port carries traffic for many VLANs over a single cable by tagging each frame with a 4-byte 802.1Q header. This chapter explains the tag format, the native VLAN concept, and the configuration on both sides of a trunk.