A Layer 3 switch is a high-performance networking device that combines the functions of a traditional switch (Layer 2) and a router (Layer 3). Operating at the data link layer (Ethernet) and the network layer (IP), it forwards traffic within a local area network (LAN) using hardware-based switching, while simultaneously performing routing between different VLANs or subnets.

Unlike a classic router, which processes packets in software, a Layer 3 switch uses specialized Application-Specific Integrated Circuits (ASICs). This hardware-based routing allows it to move inter-VLAN traffic at "wire speed," matching the throughput of a standard switch. This capability makes them ideal for network cores, where high-speed intra-network routing is required. While they excel at LAN routing, they typically lack the advanced WAN features (like NAT or VPN termination) found in dedicated routers.

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