Switches: Computing Base and New Opportunities (2023) – Definitions, Classifications, Architecture, and Applications

According to IDC data, the global switch market reached 308 billion CNY in 2022 with a 17.0% YoY growth, projected to reach 322 billion CNY in 2023 and 377 billion CNY by 2027, while China’s market accounted for 19.2% of the global share.

Switches (or “switches”) are network devices that forward electrical or optical signals, providing dedicated communication paths between any two connected nodes; the most common type is the Ethernet switch.

Based on the OSI model, switches are classified as Layer‑2 (MAC‑address based), Layer‑3 (IP‑address and protocol based), Layer‑4 (TCP/UDP port based), and higher‑layer application switches, each serving different network layers and functions.

Classification by network hierarchy includes access switches (high port density for server connections), aggregation switches (moderate bandwidth and optional services), and core switches (high‑capacity backplane for inter‑layer traffic).

Hardware components of a switch consist of chassis, power supplies, fans, backplane, management engine, system controller, line cards, and switching modules, each contributing to reliability, cooling, and data forwarding.

Common switching architectures are Full‑Mesh, CROSSBAR, and CLOS, with CLOS being the dominant design for high‑end core switches due to its scalability and non‑blocking performance.

The CLOS‑based switch board designs include non‑orthogonal (parallel), orthogonal (perpendicular), and backplane‑less structures, each with trade‑offs in signal integrity, bandwidth upgradeability, and heat dissipation.

Switches operate at the Data Link layer (OSI Layer 2), maintaining MAC address tables to forward frames only to the appropriate ports, thereby reducing broadcast domains while still allowing VLAN segmentation.

Compared with hubs, switches provide dedicated bandwidth per port and support full‑duplex communication; unlike routers, they do not perform IP routing but can segment collision domains.

Performance metrics such as backplane bandwidth, forwarding rate, and latency are critical for evaluating switch capabilities in various scenarios.

Application scenarios range from commercial switches (enterprise, campus, data‑center) to industrial switches designed for harsh environments, requiring robust temperature, EMI, and vibration resistance.

The leaf‑spine (Spine‑Leaf) architecture, a variant of the CLOS model, offers flat, low‑latency, non‑blocking connectivity ideal for modern data‑center workloads, easy scalability, and multi‑cloud management.

Industrial switches differ from commercial ones by emphasizing reliability, temperature tolerance, EMI shielding, and support for industrial protocols, often using store‑and‑forward switching to improve stability.

The switch industry chain includes upstream components (chips, modules, PCBs), mid‑stream products (managed/unmanaged, PoE, industrial, data‑center switches), and downstream deployments in telecom, cloud services, and data‑center infrastructures.