A switch learns MAC addresses from the source MAC of incoming frames and uses the CAM table to forward known unicast traffic or flood unknown traffic within the same VLAN.
CAM learning process
- Receive: the switch receives a frame on a port
- Learn: the switch reads the source MAC and stores source MAC → incoming port in the CAM table
- Lookup: the switch looks up the destination MAC in the CAM table
- Forward / flood: destination known → send out only the correct port; unknown → flood to all ports (same VLAN); broadcast/multicast → flood
Mini table (for memory)
| MAC type | What the switch does |
|---|---|
| Known unicast | Forward |
| Unknown unicast | Flood |
| Broadcast | Flood |
| Multicast | Flood (by default) |