Explain the difference between a Layer 2 switch and a Layer 3 switch, including how each forwards traffic and what role a separate router might play.

### The concept A Layer 2 switch forwards Ethernet frames within a local network by examining destination MAC addresses and consulting its MAC table. It does not use a routing table to move IP packets between separate networks, so a router must perform that Layer 3 job. A Layer 3 switch combines switching with routing. The material describes special virtual interfaces on Layer 3 switches that can act as default gateways for networks connected to the switch. A design may still use separate router and switch devices when the required routing protocols, routing-table capacity, or Layer 2 features favor separate equipment. ### What a good answer covers - Layer 2 switches forward frames using MAC addresses and a MAC table. - A Layer 2 switch does not route between IP networks, so a router is needed for that function. - A Layer 3 switch can route between networks as well as switch local frames. - Virtual interfaces on a Layer 3 switch can serve as default gateways. - Device choice can depend on routing protocols, table capacity, and other required features. ### Terms - **Layer 2**: The data-link layer, where Ethernet frames and MAC addresses are used for local delivery. - **Layer 3**: The network layer, where IP addresses are used to forward packets between networks. - **MAC**: Media Access Control. The link-layer address used for local frame delivery. - **IP**: Internet Protocol. The addressing and forwarding system used across networks. - **Router**: A device that forwards packets between networks using IP addresses and routing information. - **Routing table**: A collection of network routes used to decide where to forward packets. - **Default gateway**: The local routing interface a host uses to send traffic to other networks. - **Virtual interface**: A logical interface that can be assigned a network role without being a separate physical port. ### Remember Layer 2 switching moves frames within a network; Layer 3 routing moves packets between networks.