Linux ABC

a layer2 switch performs essentially the same function as a transparent bridge. however, a switch can have many ports and can perform hardware-based bridging. Frames are forwarded using specialized hardware, called application-specific integrated circuits(ASICs). This hardware gives switching great scalability, with wire-speed performance, low latency, low cost, and high-port density.

the router can become a bottleneck due to a latency of packet examination and processing.

Layer 3 switches are designed to examine and forward packets in high-speed LAN environments. Whereas, a router might impose a bottleneck to forwarding throughput, a Layer 3 switch can be placed anywhere in the network with little or no performance penalty.