What is a Switch?
Switching
Overview
A switch forwards frames within a broadcast domain using destination MAC information. Each port is a separate collision domain in switched Ethernet. VLANs split broadcast domains. A layer-3 switch can also route when configured, but L2 forwarding alone does not connect different IP networks.
Protocol stages
- 1Ingress port
- 2VLAN classification
- 3MAC lookup
- 4Egress decision
Interactive exercise
Knowledge check
Two ports are in different VLANs. Does ordinary L2 switching connect their broadcast traffic?
Related practice
Lab: vlan-mismatchEducational model — not real hardware, traffic or official certification.