Layer handles node-to-node delivery within a network segment. It organizes bits into frames.
Two sub-layers exist:
- LLC: error checking and flow control
- MAC: physical addressing
MAC addresses are -bit identifiers like "aa:bb:cc:dd:ee:ff" burned into network cards.
Switches operate here. A switch reads the destination MAC and forwards frames only to the correct port. Layer is local. MAC addresses don't route across the internet.