L3Switch

A layer 3 switch, or L3 switch, is a network device that combines switching and routing capabilities in a single chassis or module. It can forward packets based on both MAC addresses at layer 2 and IP addresses at layer 3, allowing inter-VLAN routing without a separate router. This enables fast communication between subnets and VLANs while maintaining high switching throughput.

Key features typically include support for multiple VLANs, inter-VLAN routing, and a range of routing options. Many L3 switches offer static routing and dynamic routing protocols such as RIP, OSPF, EIGRP, and BGP, depending on the model. They often provide hardware-based forwarding for low latency, plus features like QoS, ACLs, link aggregation, and VRFs for traffic isolation. Management interfaces may include CLI and web GUI, with monitoring and automation support via SNMP or modern APIs.

Deployment scenarios commonly involve campus networks, distribution or core layers in data centers, and branch offices where fast inter-VLAN routing is needed and dedicated routers are undesirable. L3 switches are typically placed at network aggregation points, connecting access switches to route between VLANs and to external networks. They are valued for reducing latency and simplifying network design by consolidating switching and routing.

Limitations and considerations include that some models may lack the full feature set of dedicated routers, particularly for complex WAN tasks, MPLS, or large-scale a Internet edge configurations. While high-end L3 switches support extensive routing capabilities, for certain applications a purpose-built router may still be preferred.